Three-dimensional data encoding method, three-dimensional data decoding method, three-dimensional data encoding device, three-dimensional data decoding device

ABSTRACT

A three-dimensional data encoding method includes: shifting point cloud data indicating three-dimensional positions in a three-dimensional space by a first shift amount; dividing the point cloud data into pieces of sub point cloud data; shifting each of the pieces of sub point cloud data by a second shift amount based on a position of one of the subspaces that includes the sub point cloud data, the pieces of sub point cloud data being included in the point cloud data shifted by the first shift amount; and encoding the pieces of sub point cloud data shifted, to generate a bitstream. The bitstream includes first shift information for calculating the first shift amount, and pieces of second shift information each for calculating a corresponding one of second shift amounts by which the pieces of sub point cloud data are shifted and each of which is the second shift amount.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. continuation application of PCT InternationalPatent Application Number PCT/JP2019/051535 filed on Dec. 27, 2019,claiming the benefit of priority of U.S. Provisional Patent ApplicationNo. 62/785,944 filed on Dec. 28, 2018, the entire contents of which arehereby incorporated by reference.

BACKGROUND 1. Technical Field

The present disclosure relates to a three-dimensional data encodingmethod, a three-dimensional data decoding method, a three-dimensionaldata encoding device, and a three-dimensional data decoding device.

2. Description of the Related Art

Devices or services utilizing three-dimensional data are expected tofind their widespread use in a wide range of fields, such as computervision that enables autonomous operations of cars or robots, mapinformation, monitoring, infrastructure inspection, and videodistribution. Three-dimensional data is obtained through various meansincluding a distance sensor such as a rangefinder, as well as a stereocamera and a combination of a plurality of monocular cameras.

Methods of representing three-dimensional data include a method known asa point cloud scheme that represents the shape of a three-dimensionalstructure by a point cloud in a three-dimensional space. In the pointcloud scheme, the positions and colors of a point cloud are stored.While point cloud is expected to be a mainstream method of representingthree-dimensional data, a massive amount of data of a point cloudnecessitates compression of the amount of three-dimensional data byencoding for accumulation and transmission, as in the case of atwo-dimensional moving picture (examples include Moving Picture ExpertsGroup-4 Advanced Video Coding (MPEG-4 AVC) and High Efficiency VideoCoding (HEVC) standardized by MPEG).

Meanwhile, point cloud compression is partially supported by, forexample, an open-source library (Point Cloud Library) for pointcloud-related processing.

Furthermore, a technique for searching for and displaying a facilitylocated in the surroundings of the vehicle by using three-dimensionalmap data is known (for example, see International Publication WO2014/020663).

SUMMARY

There has been a demand for improving coding efficiency in athree-dimensional data encoding process or a three-dimensional datadecoding process.

The present disclosure has an object to provide a three-dimensional dataencoding method, a three-dimensional data decoding method, athree-dimensional data encoding device, or a three-dimensional datadecoding method that is capable of improving coding efficiency.

A three-dimensional data encoding method according to one aspect of thepresent disclosure is a three-dimensional data encoding method ofencoding point cloud data indicating three-dimensional positions in athree-dimensional space, the three-dimensional data encoding methodincluding: shifting the point cloud data by a first shift amount;dividing the point cloud data into pieces of sub point cloud data bydividing the three-dimensional space into subspaces; shifting each ofthe pieces of sub point cloud data by a second shift amount based on aposition of one of the subspaces that includes the sub point cloud data,the pieces of sub point cloud data being included in the point clouddata shifted by the first shift amount; and encoding the pieces of subpoint cloud data shifted, to generate a bitstream. The bitstreamincludes first shift information for calculating the first shift amount,and pieces of second shift information each for calculating acorresponding one of second shift amounts by which the pieces of subpoint cloud data are shifted and each of which is the second shiftamount.

A three-dimensional data decoding method according to one aspect of thepresent disclosure includes: decoding pieces of sub point cloud data,first shift information, and second shift information from a bitstream,the pieces of sub point cloud data (i) being obtained by dividing pointcloud data indicating three-dimensional positions by dividing athree-dimensional space into subspaces and (ii) being each shifted by afirst shift amount and a corresponding second shift amount, the firstshift information being for calculating the first shift amount, thepieces of second shift information being each for calculating acorresponding one of second shift amounts by which the pieces of subpoint cloud data are shifted and each of which is the correspondingsecond shift amount; and restoring each of the pieces of sub point clouddata by shifting the sub point cloud data by a shift amount obtained byadding the first shift amount and the corresponding second shift amount.

The present disclosure provides a three-dimensional data encodingmethod, a three-dimensional data decoding method, a three-dimensionaldata encoding device, or a three-dimensional data decoding method thatis capable of improving coding efficiency.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the disclosure willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present disclosure.

FIG. 1 is a diagram illustrating a configuration of a three-dimensionaldata encoding and decoding system according to Embodiment 1;

FIG. 2 is a diagram illustrating a structure example of point cloud dataaccording to Embodiment 1;

FIG. 3 is a diagram illustrating a structure example of a data fileindicating the point cloud data according to Embodiment 1;

FIG. 4 is a diagram illustrating types of the point cloud data accordingto Embodiment 1;

FIG. 5 is a diagram illustrating a structure of a first encoderaccording to Embodiment 1;

FIG. 6 is a block diagram illustrating the first encoder according toEmbodiment 1;

FIG. 7 is a diagram illustrating a structure of a first decoderaccording to Embodiment 1;

FIG. 8 is a block diagram illustrating the first decoder according toEmbodiment 1;

FIG. 9 is a diagram illustrating a structure of a second encoderaccording to Embodiment 1;

FIG. 10 is a block diagram illustrating the second encoder according toEmbodiment 1;

FIG. 11 is a diagram illustrating a structure of a second decoderaccording to Embodiment 1;

FIG. 12 is a block diagram illustrating the second decoder according toEmbodiment 1;

FIG. 13 is a diagram illustrating a protocol stack related to PCCencoded data according to Embodiment 1;

FIG. 14 is a diagram illustrating a basic structure of ISOBMFF accordingto Embodiment 2;

FIG. 15 is a diagram illustrating a protocol stack according toEmbodiment 2;

FIG. 16 is a diagram illustrating an example where a NAL unit is storedin a file for codec 1 according to Embodiment 2;

FIG. 17 is a diagram illustrating an example where a NAL unit is storedin a file for codec 2 according to Embodiment 2;

FIG. 18 is a diagram illustrating a structure of a first multiplexeraccording to Embodiment 2;

FIG. 19 is a diagram illustrating a structure of a first demultiplexeraccording to Embodiment 2;

FIG. 20 is a diagram illustrating a structure of a second multiplexeraccording to Embodiment 2;

FIG. 21 is a diagram illustrating a structure of a second demultiplexeraccording to Embodiment 2;

FIG. 22 is a flowchart of processing performed by the first multiplexeraccording to Embodiment 2;

FIG. 23 is a flowchart of processing performed by the second multiplexeraccording to Embodiment 2;

FIG. 24 is a flowchart of processing performed by the firstdemultiplexer and the first decoder according to Embodiment 2;

FIG. 25 is a flowchart of processing performed by the seconddemultiplexer and the second decoder according to Embodiment 2;

FIG. 26 is a diagram illustrating structures of an encoder and a thirdmultiplexer according to Embodiment 3;

FIG. 27 is a diagram illustrating structures of a third demultiplexerand a decoder according to Embodiment 3;

FIG. 28 is a flowchart of processing performed by the third multiplexeraccording to Embodiment 3;

FIG. 29 is a flowchart of processing performed by the thirddemultiplexer and the decoder according to Embodiment 3;

FIG. 30 is a flowchart of processing performed by a three-dimensionaldata storage device according to Embodiment 3;

FIG. 31 is a flowchart of processing performed by a three-dimensionaldata acquisition device according to Embodiment 3;

FIG. 32 is a diagram illustrating structures of an encoder and amultiplexer according to Embodiment 4;

FIG. 33 is a diagram illustrating a structure example of encoded dataaccording to Embodiment 4;

FIG. 34 is a diagram illustrating a structure example of encoded dataand a NAL unit according to Embodiment 4;

FIG. 35 is a diagram illustrating a semantics example ofpcc_nal_unit_type according to Embodiment 4;

FIG. 36 is a diagram illustrating an example of a transmitting order ofNAL units according to Embodiment 4;

FIG. 37 is a diagram illustrating an example of dividing slices andtiles according to Embodiment 5;

FIG. 38 is a diagram illustrating dividing pattern examples of slicesand tiles according to Embodiment 5;

FIG. 39 is a block diagram of a first encoder according to Embodiment 6;

FIG. 40 is a block diagram of a first decoder according to Embodiment 6;

FIG. 41 is a diagram illustrating examples of a tile shape according toEmbodiment 6;

FIG. 42 is a diagram illustrating an example of tiles and slicesaccording to Embodiment 6;

FIG. 43 is a block diagram of a divider according to Embodiment 6;

FIG. 44 is a diagram illustrating an example of a map in a top view ofpoint cloud data according to Embodiment 6;

FIG. 45 is a diagram illustrating an example of tile division accordingto Embodiment 6;

FIG. 46 is a diagram illustrating an example of tile division accordingto Embodiment 6;

FIG. 47 is a diagram illustrating an example of tile division accordingto Embodiment 6;

FIG. 48 is a diagram illustrating an example of data of tiles stored ina server according to Embodiment 6;

FIG. 49 is a diagram illustrating a system regarding tile divisionaccording to Embodiment 6;

FIG. 50 is a diagram illustrating an example of slice division accordingto Embodiment 6;

FIG. 51 is a diagram illustrating an example of dependency relationshipsaccording to Embodiment 6;

FIG. 52 is a diagram illustrating an example of decoding order of dataaccording to Embodiment 6;

FIG. 53 is a diagram illustrating an example of encoded data of tilesaccording to Embodiment 6;

FIG. 54 is a block diagram of a combiner according to Embodiment 6;

FIG. 55 is a diagram illustrating a structural example of encoded dataand NAL units according to Embodiment 6;

FIG. 56 is a flowchart of an encoding process according to Embodiment 6;

FIG. 57 is a flowchart of a decoding process according to Embodiment 6;

FIG. 58 is a diagram illustrating an example of syntax of tileadditional information according to Embodiment 6;

FIG. 59 is a block diagram of an encoding and decoding system accordingto Embodiment 6;

FIG. 60 is a diagram illustrating an example of syntax of sliceadditional information according to Embodiment 6;

FIG. 61 is a flowchart of an encoding process according to Embodiment 6;

FIG. 62 is a flowchart of a decoding process according to Embodiment 6;

FIG. 63 is a flowchart of an encoding process according to Embodiment 6;

FIG. 64 is a flowchart of a decoding process according to Embodiment 6;

FIG. 65 is a diagram illustrating examples of a division methodaccording to Embodiment 7;

FIG. 66 is a diagram illustrating an example of dividing point clouddata according to Embodiment 7;

FIG. 67 is a diagram illustrating an example of syntax of tileadditional information according to Embodiment 7;

FIG. 68 is a diagram illustrating an example of index informationaccording to Embodiment 7;

FIG. 69 is a diagram illustrating an example of dependency relationshipsaccording to Embodiment 7;

FIG. 70 is a diagram illustrating an example of transmitted dataaccording to Embodiment 7;

FIG. 71 is a diagram illustrating a structural example of NAL unitsaccording to Embodiment 7;

FIG. 72 is a diagram illustrating an example of dependency relationshipsaccording to Embodiment 7;

FIG. 73 is a diagram illustrating an example of decoding order of dataaccording to Embodiment 7;

FIG. 74 is a diagram illustrating an example of dependency relationshipsaccording to Embodiment 7;

FIG. 75 is a diagram illustrating an example of decoding order of dataaccording to Embodiment 7;

FIG. 76 is a flowchart of an encoding process according to Embodiment 7;

FIG. 77 is a flowchart of a decoding process according to Embodiment 7;

FIG. 78 is a flowchart of an encoding process according to Embodiment 7;

FIG. 79 is a flowchart of an encoding process according to Embodiment 7;

FIG. 80 is a diagram illustrating an example of transmitted data and anexample of received data according to Embodiment 7;

FIG. 81 is a flowchart of a decoding process according to Embodiment 7;

FIG. 82 is a diagram illustrating an example of transmitted data and anexample of received data according to Embodiment 7;

FIG. 83 is a flowchart of a decoding process according to Embodiment 7;

FIG. 84 is a flowchart of an encoding process according to Embodiment 7;

FIG. 85 is a diagram illustrating an example of index informationaccording to Embodiment 7;

FIG. 86 is a diagram illustrating an example of dependency relationshipsaccording to Embodiment 7;

FIG. 87 is a diagram illustrating an example of transmitted dataaccording to Embodiment 7;

FIG. 88 is a diagram illustrating an example of transmitted data and anexample of received data according to Embodiment 7;

FIG. 89 is a flowchart of a decoding process according to Embodiment 7;

FIG. 90 is a flowchart of an encoding process according to Embodiment 7;

FIG. 91 is a flowchart of a decoding process according to Embodiment 7;

FIG. 92 is a block diagram illustrating an exemplary configuration of athree-dimensional data encoding device according to Embodiment 8;

FIG. 93 is a diagram for describing an overview of an encoding methodperformed by the three-dimensional data encoding device according toEmbodiment 8;

FIG. 94 is a diagram for describing a first example of position shiftaccording to Embodiment 8;

FIG. 95 is a diagram for describing a second example of the positionshift according to Embodiment 8;

FIG. 96 is a flowchart illustrating an exemplary encoding methodaccording to Embodiment 8;

FIG. 97 is a flowchart illustrating an exemplary decoding methodaccording to Embodiment 8;

FIG. 98 is a diagram for describing a third example of the positionshift according to Embodiment 8;

FIG. 99 is a flowchart illustrating an exemplary encoding methodaccording to Embodiment 8;

FIG. 100 is a flowchart illustrating an exemplary decoding methodaccording to Embodiment 8;

FIG. 101 is a diagram for describing a fourth example of the positionshift according to Embodiment 8;

FIG. 102 is a flowchart illustrating an exemplary encoding methodaccording to Embodiment 8;

FIG. 103 is a diagram for describing a fifth example of the positionshift according to Embodiment 8;

FIG. 104 is a diagram for describing an encoding method according toEmbodiment 8;

FIG. 105 is a diagram illustrating an exemplary syntax of a GPSaccording to Embodiment 8;

FIG. 106 is a diagram illustrating an exemplary syntax of a header ofgeometry information according to Embodiment 8;

FIG. 107 is a flowchart illustrating an exemplary encoding method inwhich processing is switched, according to Embodiment 8;

FIG. 108 is a flowchart illustrating an exemplary decoding method inwhich processing is switched, according to Embodiment 8;

FIG. 109 is a diagram illustrating an exemplary data structure of abitstream according to Embodiment 8;

FIG. 110 illustrates an example in which pieces of divided data in FIG.109 are replaced by frames, according to Embodiment 8;

FIG. 111 is a diagram illustrating another example of sections accordingto Embodiment 8;

FIG. 112 is a diagram illustrating another example of sections accordingto Embodiment 8;

FIG. 113 is a diagram illustrating another example of sections accordingto Embodiment 8;

FIG. 114 is a diagram illustrating another example of sections accordingto Embodiment 8;

FIG. 115 is a diagram illustrating another exemplary data structureaccording to Embodiment 8;

FIG. 116 is a diagram illustrating another exemplary data structureaccording to Embodiment 8;

FIG. 117 is a diagram illustrating another exemplary data structureaccording to Embodiment 8;

FIG. 118 is a diagram illustrating another exemplary data structureaccording to Embodiment 8;

FIG. 119 is a diagram illustrating another exemplary data structureaccording to Embodiment 8;

FIG. 120 is a flowchart of an encoding process according to Embodiment8; and

FIG. 121 is a flowchart of a decoding process according to Embodiment 8.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A three-dimensional data encoding method according to one aspect of thepresent disclosure is a three-dimensional data encoding method ofencoding point cloud data indicating three-dimensional positions in athree-dimensional space, the three-dimensional data encoding methodincluding: shifting the point cloud data by a first shift amount;dividing the point cloud data into pieces of sub point cloud data bydividing the three-dimensional space into subspaces; shifting each ofthe pieces of sub point cloud data by a second shift amount based on aposition of one of the subspaces that includes the sub point cloud data,the pieces of sub point cloud data being included in the point clouddata shifted by the first shift amount; and encoding the pieces of subpoint cloud data shifted, to generate a bitstream. The bitstreamincludes first shift information for calculating the first shift amount,and pieces of second shift information each for calculating acorresponding one of second shift amounts by which the pieces of subpoint cloud data are shifted and each of which is the second shiftamount.

According to this method, the pieces of sub point cloud data created bydividing are encoded after being shifted. This can reduce the amount ofgeometry information on each piece of sub point cloud data, therebyimproving the coding efficiency.

For example, the subspaces may be equal in size, and each of the piecesof second shift information may include first identification informationfor identifying a total number of the subspaces and a corresponding oneof the subspaces.

This can reduce the amount of the second shift information, therebyimproving the coding efficiency.

For example, the first identification information may be a Morton ordercorresponding to each of the subspaces.

For example, each of the subspaces may be a space obtained by dividingone three-dimensional space using an octree, and the bitstream mayinclude second identification information indicating that the subspaceis a space obtained by dividing one three-dimensional space using anoctree, and depth information indicating a depth of the octree.

As above, the point cloud data in the three-dimensional space is dividedusing the octree. This can reduce the amount of geometry information oneach piece of subspace point cloud data, thereby improving the codingefficiency. For example, the dividing of the point cloud data may beperformed after the point cloud data is shifted by the first shiftamount.

A three-dimensional data decoding method according to one aspect of thepresent disclosure includes: decoding pieces of sub point cloud data,first shift information, and second shift information from a bitstream,the pieces of sub point cloud data (i) being obtained by dividing pointcloud data indicating three-dimensional positions by dividing athree-dimensional space into subspaces and (ii) being each shifted by afirst shift amount and a corresponding second shift amount, the firstshift information being for calculating the first shift amount, thepieces of second shift information being each for calculating acorresponding one of second shift amounts by which the pieces of subpoint cloud data are shifted and each of which is the correspondingsecond shift amount; and restoring each of the pieces of sub point clouddata by shifting the sub point cloud data by a shift amount obtained byadding the first shift amount and the corresponding second shift amount.

According to this method, the point cloud data can be correctly decodedusing the bitstream with improved coding efficiency.

For example, the subspaces may be equal in size, and each of the piecesof second shift information may include first identification informationfor identifying a total number of the subspaces and a corresponding oneof the subspaces.

For example, the first identification information may be a Morton ordercorresponding to each of the subspaces.

For example, each of the subspaces may be a space obtained by dividingone three-dimensional space using an octree, and the bitstream mayinclude second identification information indicating that the subspaceis a space obtained by dividing one three-dimensional space using anoctree, and depth information indicating a depth of the octree.

A three-dimensional data encoding device according to one aspect of thepresent disclosure is a three-dimensional data encoding device thatencodes point cloud data indicating three-dimensional positions in athree-dimensional space, the three-dimensional data encoding deviceincluding a processor and memory. Using the memory, the processor:shifts the point cloud data by a first shift amount; divides the pointcloud data into pieces of sub point cloud data by dividing thethree-dimensional space into subspaces; divides the point cloud datainto pieces of sub point cloud data by dividing the three-dimensionalspace into subspaces; encodes the pieces of sub point cloud datashifted, to generate a bitstream. The bitstream includes first shiftinformation for calculating the first shift amount, and pieces of secondshift information each for calculating a corresponding one of secondshift amounts by which the pieces of sub point cloud data are shiftedand each of which is the second shift amount.

According to this method, the pieces of sub point cloud data created bydividing are encoded after being shifted. This can reduce the amount ofgeometry information on each piece of sub point cloud data, therebyimproving the coding efficiency.

A three-dimensional data decoding device according to one aspect of thepresent disclosure includes a processor and memory. Using the memory,the processor: decodes pieces of sub point cloud data, first shiftinformation, and second shift information from a bitstream, the piecesof sub point cloud data (i) being obtained by dividing point cloud dataindicating three-dimensional positions by dividing a three-dimensionalspace into subspaces and (ii) being each shifted by a first shift amountand a corresponding second shift amount, the first shift informationbeing for calculating the first shift amount, the pieces of second shiftinformation being each for calculating a corresponding one of secondshift amounts by which the pieces of sub point cloud data are shiftedand each of which is the corresponding second shift amount; andreproduces the point cloud data by shifting each of the pieces of subpoint cloud data by a shift amount obtained by adding the first shiftamount and the corresponding second shift amount.

According to this method, the point cloud data can be correctly decodedusing the bitstream with improved coding efficiency.

Note that these general or specific aspects may be implemented as asystem, a method, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or may beimplemented as any combination of a system, a method, an integratedcircuit, a computer program, and a recording medium.

The following describes embodiments with reference to the drawings. Notethat the following embodiments show exemplary embodiments of the presentdisclosure. The numerical values, shapes, materials, structuralcomponents, the arrangement and connection of the structural components,steps, the processing order of the steps, etc. shown in the followingembodiments are mere examples, and thus are not intended to limit thepresent disclosure. Of the structural components described in thefollowing embodiments, structural components not recited in any one ofthe independent claims that indicate the broadest concepts will bedescribed as optional structural components.

Embodiment 1

When using encoded data of a point cloud in a device or for a service inpractice, required information for the application is desirablytransmitted and received in order to reduce the network bandwidth.However, conventional encoding structures for three-dimensional datahave no such a function, and there is also no encoding method for such afunction.

Embodiment 1 described below relates to a three-dimensional dataencoding method and a three-dimensional data encoding device for encodeddata of a three-dimensional point cloud that provides a function oftransmitting and receiving required information for an application, athree-dimensional data decoding method and a three-dimensional datadecoding device for decoding the encoded data, a three-dimensional datamultiplexing method for multiplexing the encoded data, and athree-dimensional data transmission method for transmitting the encodeddata.

In particular, at present, a first encoding method and a second encodingmethod are under investigation as encoding methods (encoding schemes)for point cloud data. However, there is no method defined for storingthe configuration of encoded data and the encoded data in a systemformat. Thus, there is a problem that an encoder cannot perform an MUXprocess (multiplexing), transmission, or accumulation of data.

In addition, there is no method for supporting a format that involvestwo codecs, the first encoding method and the second encoding method,such as point cloud compression (PCC).

With regard to this embodiment, a configuration of PCC-encoded data thatinvolves two codecs, a first encoding method and a second encodingmethod, and a method of storing the encoded data in a system format willbe described.

A configuration of a three-dimensional data (point cloud data) encodingand decoding system according to this embodiment will be firstdescribed. FIG. 1 is a diagram showing an example of a configuration ofthe three-dimensional data encoding and decoding system according tothis embodiment. As shown in FIG. 1, the three-dimensional data encodingand decoding system includes three-dimensional data encoding system4601, three-dimensional data decoding system 4602, sensor terminal 4603,and external connector 4604.

Three-dimensional data encoding system 4601 generates encoded data ormultiplexed data by encoding point cloud data, which isthree-dimensional data. Three-dimensional data encoding system 4601 maybe a three-dimensional data encoding device implemented by a singledevice or a system implemented by a plurality of devices. Thethree-dimensional data encoding device may include a part of a pluralityof processors included in three-dimensional data encoding system 4601.

Three-dimensional data encoding system 4601 includes point cloud datageneration system 4611, presenter 4612, encoder 4613, multiplexer 4614,input/output unit 4615, and controller 4616. Point cloud data generationsystem 4611 includes sensor information obtainer 4617, and point clouddata generator 4618.

Sensor information obtainer 4617 obtains sensor information from sensorterminal 4603, and outputs the sensor information to point cloud datagenerator 4618. Point cloud data generator 4618 generates point clouddata from the sensor information, and outputs the point cloud data toencoder 4613.

Presenter 4612 presents the sensor information or point cloud data to auser. For example, presenter 4612 displays information or an image basedon the sensor information or point cloud data.

Encoder 4613 encodes (compresses) the point cloud data, and outputs theresulting encoded data, control information (signaling information)obtained in the course of the encoding, and other additional informationto multiplexer 4614. The additional information includes the sensorinformation, for example.

Multiplexer 4614 generates multiplexed data by multiplexing the encodeddata, the control information, and the additional information inputthereto from encoder 4613. A format of the multiplexed data is a fileformat for accumulation or a packet format for transmission, forexample.

Input/output unit 4615 (a communication unit or interface, for example)outputs the multiplexed data to the outside. Alternatively, themultiplexed data may be accumulated in an accumulator, such as aninternal memory. Controller 4616 (or an application executor) controlseach processor. That is, controller 4616 controls the encoding, themultiplexing, or other processing.

Note that the sensor information may be input to encoder 4613 ormultiplexer 4614. Alternatively, input/output unit 4615 may output thepoint cloud data or encoded data to the outside as it is.

A transmission signal (multiplexed data) output from three-dimensionaldata encoding system 4601 is input to three-dimensional data decodingsystem 4602 via external connector 4604.

Three-dimensional data decoding system 4602 generates point cloud data,which is three-dimensional data, by decoding the encoded data ormultiplexed data. Note that three-dimensional data decoding system 4602may be a three-dimensional data decoding device implemented by a singledevice or a system implemented by a plurality of devices. Thethree-dimensional data decoding device may include a part of a pluralityof processors included in three-dimensional data decoding system 4602.

Three-dimensional data decoding system 4602 includes sensor informationobtainer 4621, input/output unit 4622, demultiplexer 4623, decoder 4624,presenter 4625, user interface 4626, and controller 4627.

Sensor information obtainer 4621 obtains sensor information from sensorterminal 4603.

Input/output unit 4622 obtains the transmission signal, decodes thetransmission signal into the multiplexed data (file format or packet),and outputs the multiplexed data to demultiplexer 4623.

Demultiplexer 4623 obtains the encoded data, the control information,and the additional information from the multiplexed data, and outputsthe encoded data, the control information, and the additionalinformation to decoder 4624.

Decoder 4624 reconstructs the point cloud data by decoding the encodeddata.

Presenter 4625 presents the point cloud data to a user. For example,presenter 4625 displays information or an image based on the point clouddata. User interface 4626 obtains an indication based on a manipulationby the user. Controller 4627 (or an application executor) controls eachprocessor. That is, controller 4627 controls the demultiplexing, thedecoding, the presentation, or other processing.

Note that input/output unit 4622 may obtain the point cloud data orencoded data as it is from the outside. Presenter 4625 may obtainadditional information, such as sensor information, and presentinformation based on the additional information. Presenter 4625 mayperform a presentation based on an indication from a user obtained onuser interface 4626.

Sensor terminal 4603 generates sensor information, which is informationobtained by a sensor. Sensor terminal 4603 is a terminal provided with asensor or a camera. For example, sensor terminal 4603 is a mobile body,such as an automobile, a flying object, such as an aircraft, a mobileterminal, or a camera.

Sensor information that can be generated by sensor terminal 4603includes (1) the distance between sensor terminal 4603 and an object orthe reflectance of the object obtained by LIDAR, a millimeter waveradar, or an infrared sensor or (2) the distance between a camera and anobject or the reflectance of the object obtained by a plurality ofmonocular camera images or a stereo-camera image, for example. Thesensor information may include the posture, orientation, gyro (angularvelocity), position (GPS information or altitude), velocity, oracceleration of the sensor, for example. The sensor information mayinclude air temperature, air pressure, air humidity, or magnetism, forexample.

External connector 4604 is implemented by an integrated circuit (LSI orIC), an external accumulator, communication with a cloud server via theInternet, or broadcasting, for example.

Next, point cloud data will be described. FIG. 2 is a diagram showing aconfiguration of point cloud data. FIG. 3 is a diagram showing aconfiguration example of a data file describing information of the pointcloud data.

Point cloud data includes data on a plurality of points. Data on eachpoint includes geometry information (three-dimensional coordinates) andattribute information associated with the geometry information. A set ofa plurality of such points is referred to as a point cloud. For example,a point cloud indicates a three-dimensional shape of an object.

Geometry information (position), such as three-dimensional coordinates,may be referred to as geometry. Data on each point may include attributeinformation (attribute) on a plurality of types of attributes. A type ofattribute is color or reflectance, for example.

One piece of attribute information may be associated with one piece ofgeometry information, or attribute information on a plurality ofdifferent types of attributes may be associated with one piece ofgeometry information. Alternatively, a plurality of pieces of attributeinformation on the same type of attribute may be associated with onepiece of geometry information.

The configuration example of a data file shown in FIG. 3 is an examplein which geometry information and attribute information are associatedwith each other in a one-to-one relationship, and geometry informationand attribute information on N points forming point cloud data areshown.

The geometry information is information on three axes, specifically, anx-axis, a y-axis, and a z-axis, for example. The attribute informationis RGB color information, for example. A representative data file is plyfile, for example.

Next, types of point cloud data will be described. FIG. 4 is a diagramshowing types of point cloud data. As shown in FIG. 4, point cloud dataincludes a static object and a dynamic object.

The static object is three-dimensional point cloud data at an arbitrarytime (a time point). The dynamic object is three-dimensional point clouddata that varies with time. In the following, three-dimensional pointcloud data associated with a time point will be referred to as a PCCframe or a frame.

The object may be a point cloud whose range is limited to some extent,such as ordinary video data, or may be a large point cloud whose rangeis not limited, such as map information.

There are point cloud data having varying densities. There may be sparsepoint cloud data and dense point cloud data.

In the following, each processor will be described in detail. Sensorinformation is obtained by various means, including a distance sensorsuch as LIDAR or a range finder, a stereo camera, or a combination of aplurality of monocular cameras. Point cloud data generator 4618generates point cloud data based on the sensor information obtained bysensor information obtainer 4617. Point cloud data generator 4618generates geometry information as point cloud data, and adds attributeinformation associated with the geometry information to the geometryinformation.

When generating geometry information or adding attribute information,point cloud data generator 4618 may process the point cloud data. Forexample, point cloud data generator 4618 may reduce the data amount byomitting a point cloud whose position coincides with the position ofanother point cloud. Point cloud data generator 4618 may also convertthe geometry information (such as shifting, rotating or normalizing theposition) or render the attribute information.

Note that, although FIG. 1 shows point cloud data generation system 4611as being included in three-dimensional data encoding system 4601, pointcloud data generation system 4611 may be independently provided outsidethree-dimensional data encoding system 4601.

Encoder 4613 generates encoded data by encoding point cloud dataaccording to an encoding method previously defined. In general, thereare the two types of encoding methods described below. One is anencoding method using geometry information, which will be referred to asa first encoding method, hereinafter. The other is an encoding methodusing a video codec, which will be referred to as a second encodingmethod, hereinafter.

Decoder 4624 decodes the encoded data into the point cloud data usingthe encoding method previously defined.

Multiplexer 4614 generates multiplexed data by multiplexing the encodeddata in an existing multiplexing method. The generated multiplexed datais transmitted or accumulated. Multiplexer 4614 multiplexes not only thePCC-encoded data but also another medium, such as a video, an audio,subtitles, an application, or a file, or reference time information.Multiplexer 4614 may further multiplex attribute information associatedwith sensor information or point cloud data.

Multiplexing schemes or file formats include ISOBMFF, MPEG-DASH, whichis a transmission scheme based on ISOBMFF, MMT, MPEG-2 TS Systems, orRMP, for example.

Demultiplexer 4623 extracts PCC-encoded data, other media, timeinformation and the like from the multiplexed data.

Input/output unit 4615 transmits the multiplexed data in a methodsuitable for the transmission medium or accumulation medium, such asbroadcasting or communication. Input/output unit 4615 may communicatewith another device over the Internet or communicate with anaccumulator, such as a cloud server.

As a communication protocol, http, ftp, TCP, UDP or the like is used.The pull communication scheme or the push communication scheme can beused.

A wired transmission or a wireless transmission can be used. For thewired transmission, Ethernet (registered trademark), USB, RS-232C, HDMI(registered trademark), or a coaxial cable is used, for example. For thewireless transmission, wireless LAN, Wi-Fi (registered trademark),Bluetooth (registered trademark), or a millimeter wave is used, forexample.

As a broadcasting scheme, DVB-T2, DVB-S2, DVB-C2, ATSC3.0, or ISDB-S3 isused, for example.

FIG. 5 is a diagram showing a configuration of first encoder 4630, whichis an example of encoder 4613 that performs encoding in the firstencoding method. FIG. 6 is a block diagram showing first encoder 4630.First encoder 4630 generates encoded data (encoded stream) by encodingpoint cloud data in the first encoding method. First encoder 4630includes geometry information encoder 4631, attribute informationencoder 4632, additional information encoder 4633, and multiplexer 4634.

First encoder 4630 is characterized by performing encoding by keeping athree-dimensional structure in mind. First encoder 4630 is furthercharacterized in that attribute information encoder 4632 performsencoding using information obtained from geometry information encoder4631. The first encoding method is referred to also as geometry-basedPCC (GPCC).

Point cloud data is PCC point cloud data like a PLY file or PCC pointcloud data generated from sensor information, and includes geometryinformation (position), attribute information (attribute), and otheradditional information (metadata). The geometry information is input togeometry information encoder 4631, the attribute information is input toattribute information encoder 4632, and the additional information isinput to additional information encoder 4633.

Geometry information encoder 4631 generates encoded geometry information(compressed geometry), which is encoded data, by encoding geometryinformation. For example, geometry information encoder 4631 encodesgeometry information using an N-ary tree structure, such as an octree.Specifically, in the case of an octree, a current space is divided intoeight nodes (subspaces), 8-bit information (occupancy code) thatindicates whether each node includes a point cloud or not is generated.A node including a point cloud is further divided into eight nodes, and8-bit information that indicates whether each of the eight nodesincludes a point cloud or not is generated. This process is repeateduntil a predetermined level is reached or the number of the point cloudsincluded in each node becomes equal to or less than a threshold.

Attribute information encoder 4632 generates encoded attributeinformation (compressed attribute), which is encoded data, by encodingattribute information using configuration information generated bygeometry information encoder 4631. For example, attribute informationencoder 4632 determines a reference point (reference node) that is to bereferred to in encoding a current point (current node) to be processedbased on the octree structure generated by geometry information encoder4631. For example, attribute information encoder 4632 refers to a nodewhose parent node in the octree is the same as the parent node of thecurrent node, of peripheral nodes or neighboring nodes. Note that themethod of determining a reference relationship is not limited to thismethod.

The process of encoding attribute information may include at least oneof a quantization process, a prediction process, and an arithmeticencoding process. In this case, “refer to” means using a reference nodefor calculating a predicted value of attribute information or using astate of a reference node (occupancy information that indicates whethera reference node includes a point cloud or not, for example) fordetermining a parameter of encoding. For example, the parameter ofencoding is a quantization parameter in the quantization process or acontext or the like in the arithmetic encoding.

Additional information encoder 4633 generates encoded additionalinformation (compressed metadata), which is encoded data, by encodingcompressible data of additional information.

Multiplexer 4634 generates encoded stream (compressed stream), which isencoded data, by multiplexing encoded geometry information, encodedattribute information, encoded additional information, and otheradditional information. The generated encoded stream is output to aprocessor in a system layer (not shown).

Next, first decoder 4640, which is an example of decoder 4624 thatperforms decoding in the first encoding method, will be described. FIG.7 is a diagram showing a configuration of first decoder 4640. FIG. 8 isa block diagram showing first decoder 4640. First decoder 4640 generatespoint cloud data by decoding encoded data (encoded stream) encoded inthe first encoding method in the first encoding method. First decoder4640 includes demultiplexer 4641, geometry information decoder 4642,attribute information decoder 4643, and additional information decoder4644.

An encoded stream (compressed stream), which is encoded data, is inputto first decoder 4640 from a processor in a system layer (not shown).

Demultiplexer 4641 separates encoded geometry information (compressedgeometry), encoded attribute information (compressed attribute), encodedadditional information (compressed metadata), and other additionalinformation from the encoded data.

Geometry information decoder 4642 generates geometry information bydecoding the encoded geometry information. For example, geometryinformation decoder 4642 restores the geometry information on a pointcloud represented by three-dimensional coordinates from encoded geometryinformation represented by an N-ary structure, such as an octree.

Attribute information decoder 4643 decodes the encoded attributeinformation based on configuration information generated by geometryinformation decoder 4642. For example, attribute information decoder4643 determines a reference point (reference node) that is to bereferred to in decoding a current point (current node) to be processedbased on the octree structure generated by geometry information decoder4642. For example, attribute information decoder 4643 refers to a nodewhose parent node in the octree is the same as the parent node of thecurrent node, of peripheral nodes or neighboring nodes. Note that themethod of determining a reference relationship is not limited to thismethod.

The process of decoding attribute information may include at least oneof an inverse quantization process, a prediction process, and anarithmetic decoding process. In this case, “refer to” means using areference node for calculating a predicted value of attributeinformation or using a state of a reference node (occupancy informationthat indicates whether a reference node includes a point cloud or not,for example) for determining a parameter of decoding. For example, theparameter of decoding is a quantization parameter in the inversequantization process or a context or the like in the arithmeticdecoding.

Additional information decoder 4644 generates additional information bydecoding the encoded additional information. First decoder 4640 usesadditional information required for the decoding process for thegeometry information and the attribute information in the decoding, andoutputs additional information required for an application to theoutside.

Next, second encoder 4650, which is an example of encoder 4613 thatperforms encoding in the second encoding method, will be described. FIG.9 is a diagram showing a configuration of second encoder 4650. FIG. 10is a block diagram showing second encoder 4650.

Second encoder 4650 generates encoded data (encoded stream) by encodingpoint cloud data in the second encoding method. Second encoder 4650includes additional information generator 4651, geometry image generator4652, attribute image generator 4653, video encoder 4654, additionalinformation encoder 4655, and multiplexer 4656.

Second encoder 4650 is characterized by generating a geometry image andan attribute image by projecting a three-dimensional structure onto atwo-dimensional image, and encoding the generated geometry image andattribute image in an existing video encoding scheme. The secondencoding method is referred to as video-based PCC (VPCC).

Point cloud data is PCC point cloud data like a PLY file or PCC pointcloud data generated from sensor information, and includes geometryinformation (position), attribute information (attribute), and otheradditional information (metadata).

Additional information generator 4651 generates map information on aplurality of two-dimensional images by projecting a three-dimensionalstructure onto a two-dimensional image.

Geometry image generator 4652 generates a geometry image based on thegeometry information and the map information generated by additionalinformation generator 4651. The geometry image is a distance image inwhich distance (depth) is indicated as a pixel value, for example. Thedistance image may be an image of a plurality of point clouds viewedfrom one point of view (an image of a plurality of point cloudsprojected onto one two-dimensional plane), a plurality of images of aplurality of point clouds viewed from a plurality of points of view, ora single image integrating the plurality of images.

Attribute image generator 4653 generates an attribute image based on theattribute information and the map information generated by additionalinformation generator 4651. The attribute image is an image in whichattribute information (color (RGB), for example) is indicated as a pixelvalue, for example. The image may be an image of a plurality of pointclouds viewed from one point of view (an image of a plurality of pointclouds projected onto one two-dimensional plane), a plurality of imagesof a plurality of point clouds viewed from a plurality of points ofview, or a single image integrating the plurality of images.

Video encoder 4654 generates an encoded geometry image (compressedgeometry image) and an encoded attribute image (compressed attributeimage), which are encoded data, by encoding the geometry image and theattribute image in a video encoding scheme. Note that, as the videoencoding scheme, any well-known encoding method can be used. Forexample, the video encoding scheme is AVC or HEVC.

Additional information encoder 4655 generates encoded additionalinformation (compressed metadata) by encoding the additionalinformation, the map information and the like included in the pointcloud data.

Multiplexer 4656 generates an encoded stream (compressed stream), whichis encoded data, by multiplexing the encoded geometry image, the encodedattribute image, the encoded additional information, and otheradditional information. The generated encoded stream is output to aprocessor in a system layer (not shown).

Next, second decoder 4660, which is an example of decoder 4624 thatperforms decoding in the second encoding method, will be described. FIG.11 is a diagram showing a configuration of second decoder 4660. FIG. 12is a block diagram showing second decoder 4660. Second decoder 4660generates point cloud data by decoding encoded data (encoded stream)encoded in the second encoding method in the second encoding method.Second decoder 4660 includes demultiplexer 4661, video decoder 4662,additional information decoder 4663, geometry information generator4664, and attribute information generator 4665.

An encoded stream (compressed stream), which is encoded data, is inputto second decoder 4660 from a processor in a system layer (not shown).

Demultiplexer 4661 separates an encoded geometry image (compressedgeometry image), an encoded attribute image (compressed attributeimage), an encoded additional information (compressed metadata), andother additional information from the encoded data.

Video decoder 4662 generates a geometry image and an attribute image bydecoding the encoded geometry image and the encoded attribute image in avideo encoding scheme. Note that, as the video encoding scheme, anywell-known encoding method can be used. For example, the video encodingscheme is AVC or HEVC.

Additional information decoder 4663 generates additional informationincluding map information or the like by decoding the encoded additionalinformation.

Geometry information generator 4664 generates geometry information fromthe geometry image and the map information. Attribute informationgenerator 4665 generates attribute information from the attribute imageand the map information.

Second decoder 4660 uses additional information required for decoding inthe decoding, and outputs additional information required for anapplication to the outside.

In the following, a problem with the PCC encoding scheme will bedescribed. FIG. 13 is a diagram showing a protocol stack relating toPCC-encoded data. FIG. 13 shows an example in which PCC-encoded data ismultiplexed with other medium data, such as a video (HEVC, for example)or an audio, and transmitted or accumulated.

A multiplexing scheme and a file format have a function of multiplexingvarious encoded data and transmitting or accumulating the data. Totransmit or accumulate encoded data, the encoded data has to beconverted into a format for the multiplexing scheme. For example, withHEVC, a technique for storing encoded data in a data structure referredto as a NAL unit and storing the NAL unit in ISOBMFF is prescribed.

At present, a first encoding method (Codec1) and a second encodingmethod (Codec2) are under investigation as encoding methods for pointcloud data. However, there is no method defined for storing theconfiguration of encoded data and the encoded data in a system format.Thus, there is a problem that an encoder cannot perform an MUX process(multiplexing), transmission, or accumulation of data.

Note that, in the following, the term “encoding method” means any of thefirst encoding method and the second encoding method unless a particularencoding method is specified.

Embodiment 2

In Embodiment 2, a method of storing the NAL unit in an ISOBMFF filewill be described.

ISOBMFF is a file format standard prescribed in ISO/IEC14496-12. ISOBMFFis a standard that does not depend on any medium, and prescribes aformat that allows various media, such as a video, an audio, and a text,to be multiplexed and stored.

A basic structure (file) of ISOBMFF will be described. A basic unit ofISOBMFF is a box. A box is formed by type, length, and data, and a fileis a set of various types of boxes.

FIG. 14 is a diagram showing a basic structure (file) of ISOBMFF. A filein ISOBMFF includes boxes, such as ftyp that indicates the brand of thefile by four-character code (4CC), moov that stores metadata, such ascontrol information (signaling information), and mdat that stores data.

A method for storing each medium in the ISOBMFF file is separatelyprescribed. For example, a method of storing an AVC video or an HEVCvideo is prescribed in ISO/IEC14496-15. Here, it can be contemplated toexpand the functionality of ISOBMFF and use ISOBMFF to accumulate ortransmit PCC-encoded data. However, there has been no convention forstoring PCC-encoded data in an ISOBMFF file. In this embodiment, amethod of storing PCC-encoded data in an ISOBMFF file will be described.

FIG. 15 is a diagram showing a protocol stack in a case where a commonPCC codec NAL unit in an ISOBMFF file. Here, a common PCC codec NAL unitis stored in an ISOBMFF file. Although the NAL unit is common to PCCcodecs, a storage method for each codec (Carriage of Codec1, Carriage ofCodec2) is desirably prescribed, since a plurality of PCC codecs arestored in the NAL unit.

Next, a method of storing a common PCC NAL unit that supports aplurality of PCC codecs in an ISOBMFF file will be described. FIG. 16 isa diagram showing an example in which a common PCC NAL unit is stored inan ISOBMFF file for the storage method for codec 1 (Carriage of Codec1).FIG. 17 is a diagram showing an example in which a common PCC NAL unitis stored in an ISOBMFF file for the storage method for codec 2(Carriage of Codec2).

Here, ftyp is information that is important for identification of thefile format, and a different identifier of ftyp is defined for eachcodec. When PCC-encoded data encoded in the first encoding method(encoding scheme) is stored in the file, ftyp is set to pcc1. WhenPCC-encoded data encoded in the second encoding method is stored in thefile, ftyp is set to pcc2.

Here, pcc1 indicates that PCC codec 1 (first encoding method) is used.pcc2 indicates that PCC codec2 (second encoding method) is used. Thatis, pcc1 and pcc2 indicate that the data is PCC (encodedthree-dimensional data (point cloud data)), and indicate the PCC codec(first encoding method or second encoding method).

In the following, a method of storing a NAL unit in an ISOBMFF file willbe described. The multiplexer analyzes the NAL unit header, anddescribes pcc1 in ftyp of ISOBMFF if pcc_codec_type=Codec1.

The multiplexer analyzes the NAL unit header, and describes pcc2 in ftypof ISOBMFF if pcc_codec_type=Codec2.

If pcc_nal_unit_type is metadata, the multiplexer stores the NAL unit inmoov or mdat in a predetermined manner, for example. Ifpcc_nal_unit_type is data, the multiplexer stores the NAL unit in moovor mdat in a predetermined manner, for example.

For example, the multiplexer may store the NAL unit size in the NALunit, as with HEVC.

According to this storage method, the demultiplexer (a system layer) candetermine whether the PCC-encoded data is encoded in the first encodingmethod or the second encoding method by analyzing ftyp included in thefile. Furthermore, as described above, by determining whether thePCC-encoded data is encoded in the first encoding method or the secondencoding method, the encoded data encoded in any one of the encodingmethods can be extracted from the data including both the encoded dataencoded in the encoding methods. Therefore, when transmitting theencoded data, the amount of data transmitted can be reduced. Inaddition, according to this storage method, different data (file)formats do not need to be set for the first encoding method and thesecond encoding method, and a common data format can be used for thefirst encoding method and the second encoding method.

Note that, when the identification information for the codec, such asftyp of ISOBMFF, is indicated in the metadata of the system layer, themultiplexer can store a NAL unit without pcc_nal_unit_type in theISOBMFF file.

Next, configurations and operations of the multiplexer of thethree-dimensional data encoding system (three-dimensional data encodingdevice) according to this embodiment and the demultiplexer of thethree-dimensional data decoding system (three-dimensional data decodingdevice) according to this embodiment will be described.

FIG. 18 is a diagram showing a configuration of first multiplexer 4710.First multiplexer 4710 includes file converter 4711 that generatesmultiplexed data (file) by storing encoded data generated by firstencoder 4630 and control information (NAL unit) in an ISOBMFF file.First multiplexer 4710 is included in multiplexer 4614 shown in FIG. 1,for example.

FIG. 19 is a diagram showing a configuration of first demultiplexer4720. First demultiplexer 4720 includes file inverse converter 4721 thatobtains encoded data and control information (NAL unit) from multiplexeddata (file) and outputs the obtained encoded data and controlinformation to first decoder 4640. First demultiplexer 4720 is includedin demultiplexer 4623 shown in FIG. 1, for example.

FIG. 20 is a diagram showing a configuration of second multiplexer 4730.Second multiplexer 4730 includes file converter 4731 that generatesmultiplexed data (file) by storing encoded data generated by secondencoder 4650 and control information (NAL unit) in an ISOBMFF file.Second multiplexer 4730 is included in multiplexer 4614 shown in FIG. 1,for example.

FIG. 21 is a diagram showing a configuration of second demultiplexer4740. Second demultiplexer 4740 includes file inverse converter 4741that obtains encoded data and control information (NAL unit) frommultiplexed data (file) and outputs the obtained encoded data andcontrol information to second decoder 4660. Second demultiplexer 4740 isincluded in demultiplexer 4623 shown in FIG. 1, for example.

FIG. 22 is a flowchart showing a multiplexing process by firstmultiplexer 4710. First, first multiplexer 4710 analyzes pcc_codec_typein the NAL unit header, thereby determining whether the codec used isthe first encoding method or the second encoding method (S4701).

When pcc_codec_type represents the second encoding method (if “secondencoding method” in S4702), first multiplexer 4710 does not process theNAL unit (S4703).

On the other hand, when pcc_codec_type represents the first encodingmethod (if “first encoding method” in S4702), first multiplexer 4710describes pcc1 in ftyp (S4704). That is, first multiplexer 4710describes information indicating that data encoded in the first encodingmethod is stored in the file in ftyp.

First multiplexer 4710 then analyzes pcc_nal_unit_type in the NAL unitheader, and stores the data in a box (moov or mdat, for example) in apredetermined manner suitable for the data type represented bypcc_nal_unit_type (S4705). First multiplexer 4710 then creates anISOBMFF file including the ftyp described above and the box describedabove (S4706).

FIG. 23 is a flowchart showing a multiplexing process by secondmultiplexer 4730. First, second multiplexer 4730 analyzes pcc_codec_typein the NAL unit header, thereby determining whether the codec used isthe first encoding method or the second encoding method (S4711).

When pcc_codec_type represents the second encoding method (if “secondencoding method” in S4712), second multiplexer 4730 describes pcc2 inftyp (S4713). That is, second multiplexer 4730 describes informationindicating that data encoded in the second encoding method is stored inthe file in ftyp.

Second multiplexer 4730 then analyzes pcc_nal_unit_type in the NAL unitheader, and stores the data in a box (moov or mdat, for example) in apredetermined manner suitable for the data type represented bypcc_nal_unit_type (S4714). Second multiplexer 4730 then creates anISOBMFF file including the ftyp described above and the box describedabove (S4715).

On the other hand, when pcc_codec_type represents the first encodingmethod (if “first encoding method” in S4712), second multiplexer 4730does not process the NAL unit (S4716).

Note that the process described above is an example in which PCC data isencoded in any one of the first encoding method and the second encodingmethod. First multiplexer 4710 and second multiplexer 4730 store adesired NAL unit in a file by identifying the codec type of the NALunit. Note that, when the identification information for the PCC codecis included in a location other than the NAL unit header, firstmultiplexer 4710 and second multiplexer 4730 may identify the codec type(first encoding method or second encoding method) based on theidentification information for the PCC codec included in the locationother than the NAL unit header in step S4701 or S4711.

When storing data in a file in step S4706 or S4714, first multiplexer4710 and second multiplexer 4730 may store the data in the file afterdeleting pcc_nal_unit_type from the NAL unit header.

FIG. 24 is a flowchart showing a process performed by firstdemultiplexer 4720 and first decoder 4640. First, first demultiplexer4720 analyzes ftyp in an ISOBMFF file (S4721). When the codecrepresented by ftyp is the second encoding method (pcc2) (if “secondencoding method” in S4722), first demultiplexer 4720 determines that thedata included in the payload of the NAL unit is data encoded in thesecond encoding method (S4723). First demultiplexer 4720 also transmitsthe result of the determination to first decoder 4640. First decoder4640 does not process the NAL unit (S4724).

On the other hand, when the codec represented by ftyp is the firstencoding method (pcc1) (if “first encoding method” in S4722), firstdemultiplexer 4720 determines that the data included in the payload ofthe NAL unit is data encoded in the first encoding method (S4725). Firstdemultiplexer 4720 also transmits the result of the determination tofirst decoder 4640.

First decoder 4640 identifies the data based on the determination thatpcc_nal_unit_type in the NAL unit header is the identifier of the NALunit for the first encoding method (S4726). First decoder 4640 thendecodes the PCC data using a decoding process for the first encodingmethod (S4727).

FIG. 25 is a flowchart showing a process performed by seconddemultiplexer 4740 and second decoder 4660. First, second demultiplexer4740 analyzes ftyp in an ISOBMFF file (S4731). When the codecrepresented by ftyp is the second encoding method (pcc2) (if “secondencoding method” in S4732), second demultiplexer 4740 determines thatthe data included in the payload of the NAL unit is data encoded in thesecond encoding method (S4733). Second demultiplexer 4740 also transmitsthe result of the determination to second decoder 4660.

Second decoder 4660 identifies the data based on the determination thatpcc_nal_unit_type in the NAL unit header is the identifier of the NALunit for the second encoding method (S4734). Second decoder 4660 thendecodes the PCC data using a decoding process for the second encodingmethod (S4735).

On the other hand, when the codec represented by ftyp is the firstencoding method (pcc1) (if “first encoding method” in S4732), seconddemultiplexer 4740 determines that the data included in the payload ofthe NAL unit is data encoded in the first encoding method (S4736).Second demultiplexer 4740 also transmits the result of the determinationto second decoder 4660. Second decoder 4660 does not process the NALunit (S4737).

As described above, for example, since the codec type of the NAL unit isidentified in first demultiplexer 4720 or second demultiplexer 4740, thecodec type can be identified in an early stage. Furthermore, a desiredNAL unit can be input to first decoder 4640 or second decoder 4660, andan unwanted NAL unit can be removed. In this case, the process of firstdecoder 4640 or second decoder 4660 analyzing the identificationinformation for the codec may be unnecessary. Note that a process ofreferring to the NAL unit type again and analyzing the identificationinformation for the codec may be performed by first decoder 4640 orsecond decoder 4660.

Furthermore, if pcc_nal_unit_type is deleted from the NAL unit header byfirst multiplexer 4710 or second multiplexer 4730, first demultiplexer4720 or second demultiplexer 4740 can output the NAL unit to firstdecoder 4640 or second decoder 4660 after adding pcc_nal_unit_type tothe NAL unit.

Embodiment 3

In Embodiment 3, a multiplexer and a demultiplexer that correspond toencoder 4670 and decoder 4680 ready for a plurality of codecs describedabove with regard to Embodiment 1 will be described. FIG. 26 is adiagram showing configurations of encoder 4670 and third multiplexer4750 according to this embodiment.

Encoder 4670 encodes point cloud data in both or one of the firstencoding method and the second encoding method. Encoder 4670 may changethe encoding method (between the first encoding method and the secondencoding method) on a point-cloud-data basis or on a frame basis.Alternatively, encoder 4670 may change the encoding method on the basisof an encodable unit.

Encoder 4670 generates encoded data (encoded stream) including theidentification information for a PCC codec.

Third multiplexer 4750 includes file converter 4751. File converter 4751converts a NAL unit output from encoder 4670 into a PCC data file. Fileconverter 4751 analyzes the codec identification information included inthe NAL unit header, and determines whether the PCC-encoded data is dataencoded in the first encoding method, data encoded in the secondencoding method, or data encoded in both the encoding methods. Fileconverter 4751 describes a brand name that allows codec identificationin ftyp. For example, when indicating the data is encoded in both theencoding methods, pcc3 is described in ftyp.

Note that, when encoder 4670 describes the PCC codec identificationinformation in a location other than the NAL unit, file converter 4751may determine the PCC codec (encoding method) based on theidentification information.

FIG. 27 is a diagram showing configurations of third demultiplexer 4760and decoder 4680 according to this embodiment.

Third demultiplexer 4760 includes file inverse converter 4761. Fileinverse converter 4761 analyzes ftyp included in a file, and determineswhether the PCC-encoded data is data encoded in the first encodingmethod, data encoded in the second encoding method, or data encoded inboth the encoding methods.

When the PCC-encoded data is data encoded in any one of the encodingmethods, the data is input to an appropriate one of first decoder 4640and second decoder 4660, and is not input to the other decoder. When thePCC-encoded data is data encoded in both the encoding methods, the datais input to decoder 4680 ready for both the encoding methods.

Decoder 4680 decodes the PCC-encoded data in both or one of the firstencoding method and the second encoding method.

FIG. 28 is a flowchart showing a process performed by third multiplexer4750 according to this embodiment.

First, third multiplexer 4750 analyzes pcc_codec_type in the NAL unitheader, thereby determining whether the codec(s) used is the firstencoding method, the second encoding method, or both the first encodingmethod and the second encoding method (S4741).

When the second encoding method is used (if Yes in S4742 and “secondencoding method” in S4743), third multiplexer 4750 describes pcc2 inftyp (S4744). That is, third multiplexer 4750 describes informationindicating that data encoded in the second encoding method is stored inthe file in ftyp.

Third multiplexer 4750 then analyzes pcc_nal_unit_type in the NAL unitheader, and stores the data in a box (moov or mdat, for example) in apredetermined manner suitable for the data type represented bypcc_nal_unit_type (S4745). Third multiplexer 4750 then creates anISOBMFF file including the ftyp described above and the box describedabove (S4746).

When the first encoding method is used (if Yes in S4742 and “firstencoding method” in S4743), third multiplexer 4750 describes pcc1 inftyp (S4747). That is, third multiplexer 4750 describes informationindicating that data encoded in the first encoding method is stored inthe file in ftyp.

Third multiplexer 4750 then analyzes pcc_nal_unit_type in the NAL unitheader, and stores the data in a box (moov or mdat, for example) in apredetermined manner suitable for the data type represented bypcc_nal_unit_type (S4748). Third multiplexer 4750 then creates anISOBMFF file including the ftyp described above and the box describedabove (S4746).

When both the first encoding method and the second encoding method areused (if No in S4742), third multiplexer 4750 describes pcc3 in ftyp(S4749). That is, third multiplexer 4750 describes informationindicating that data encoded in both the encoding methods is stored inthe file in ftyp.

Third multiplexer 4750 then analyzes pcc_nal_unit_type in the NAL unitheader, and stores the data in a box (moov or mdat, for example) in apredetermined manner suitable for the data type represented bypcc_nal_unit_type (S4750). Third multiplexer 4750 then creates anISOBMFF file including the ftyp described above and the box describedabove (S4746).

FIG. 29 is a flowchart showing a process performed by thirddemultiplexer 4760 and decoder 4680. First, third demultiplexer 4760analyzes ftyp included in an ISOBMFF file (S4761). When the codecrepresented by ftyp is the second encoding method (pcc2) (if Yes inS4762 and “second encoding method” in S4763), third demultiplexer 4760determines that the data included in the payload of the NAL unit is dataencoded in the second encoding method (S4764). Third demultiplexer 4760also transmits the result of the determination to decoder 4680.

Decoder 4680 identifies the data based on the determination thatpcc_nal_unit_type in the NAL unit header is the identifier of the NALunit for the second encoding method (S4765). Decoder 4680 then decodesthe PCC data using a decoding process for the second encoding method(S4766).

When the codec represented by ftyp is the first encoding method (pcc1)(if Yes in S4762 and “first encoding method” in S4763), thirddemultiplexer 4760 determines that the data included in the payload ofthe NAL unit is data encoded in the first encoding method (S4767). Thirddemultiplexer 4760 also transmits the result of the determination todecoder 4680.

Decoder 4680 identifies the data based on the determination thatpcc_nal_unit_type in the NAL unit header is the identifier of the NALunit for the first encoding method (S4768). Decoder 4680 then decodesthe PCC data using a decoding process for the first encoding method(S4769).

When ftyp indicates that both the encoding methods are used (pcc3) (ifNo in S4762), third demultiplexer 4760 determines that the data includedin the payload of the NAL unit is data encoded in both the firstencoding method and the second encoding method (S4770). Thirddemultiplexer 4760 also transmits the result of the determination todecoder 4680.

Decoder 4680 identifies the data based on the determination thatpcc_nal_unit_type in the NAL unit header is the identifier of the NALunit for the codecs described in pcc_codec_type (S4771). Decoder 4680then decodes the PCC data using decoding processes for both the encodingmethods (S4772). That is, decoder 4680 decodes the data encoded in thefirst encoding method using a decoding process for the first encodingmethod, and decodes the data encoded in the second encoding method usinga decoding process for the second encoding method.

In the following, variations of this embodiment will be described. Astypes of brands represented by ftyp, the types described below can beindicated by the identification information. Furthermore, a combinationof a plurality of the types described below can also be indicated by theidentification information.

The identification information may indicate whether the original dataobject yet to be PCC-encoded is a point cloud whose range is limited ora large point cloud whose range is not limited, such as map information.

The identification information may indicate whether the original datayet to be PCC-encoded is a static object or a dynamic object.

As described above, the identification information may indicate whetherthe PCC-encoded data is data encoded in the first encoding method ordata encoded in the second encoding method.

The identification information may indicate an algorithm used in the PCCencoding. Here, the “algorithm” means an encoding method that can beused in the first encoding method or the second encoding method, forexample.

The identification information may indicate a differentiation betweenmethods of storing the PCC-encoded data into an ISOBMFF file. Forexample, the identification information may indicate whether the storagemethod used is a storage method for accumulation or a storage method forreal-time transmission, such as dynamic streaming.

Although an example in which ISOBMFF is used as a file format has beendescribed in Embodiments 2 and 3, other formats can also be used. Forexample, the method according to this embodiment can also be used whenPCC-encoded data is stored in MPEG-2 TS Systems, MPEG-DASH, MMT, or RMP.

Although an example in which metadata, such as the identificationinformation, is stored in ftyp has been shown above, metadata can alsobe stored in a location other than ftyp. For example, the metadata maybe stored in moov.

As described above, a three-dimensional data storing device (orthree-dimensional data multiplexing device or three-dimensional dataencoding device) performs the process shown in FIG. 30.

First, the three-dimensional data storing device (which includes firstmultiplexer 4710, second multiplexer 4730 or third multiplexer 4750, forexample) acquires one or more units (NAL units, for example) that storean encoded stream, which is encoded point cloud data (S4781). Thethree-dimensional data storing device then stores the one or more unitsin a file (an ISOBMFF file, for example) (S4782). In the storage(S4782), the three-dimensional data storing device also storesinformation indicating that the data stored in the file is encoded pointcloud data (pcc1, pcc2, or pcc3, for example) in the control information(ftyp, for example) (referred to also as signaling information) for thefile.

With such a configuration, a device that processes the file generated bythe three-dimensional data storing device can quickly determine whetherthe data stored in the file is encoded point cloud data or not byreferring to the control information for the file. Therefore, theprocessing amount of the device can be reduced, or the processing speedof the device can be increased.

For example, the information indicates the encoding method used for theencoding of the point cloud data among the first encoding method and thesecond encoding method. Note that the fact that the data stored in thefile is encoded point cloud data and the encoding method used for theencoding of the point cloud data among the first encoding method and thesecond encoding method may be indicated by a single piece of informationor different pieces of information.

With such a configuration, a device that processes the file generated bythe three-dimensional data storing device can quickly determine thecodec used for the data stored in the file by referring to the controlinformation for the file. Therefore, the processing amount of the devicecan be reduced, or the processing speed of the device can be increased.

For example, the first encoding method is a method (GPCC) that encodesgeometry information that represents the position of point cloud data asan N-ary tree (N represents an integer equal to or greater than 2) andencodes attribute information using the geometry information, and thesecond encoding method is a method (VPCC) that generates atwo-dimensional image from point cloud data and encodes thetwo-dimensional image in a video encoding method.

For example, the file described above is in conformity with ISOBMFF(ISO-based media file format).

For example, the three-dimensional data storing device includes aprocessor and a memory, and the processor performs the processesdescribed above using the memory.

As described above, a three-dimensional data acquisition device (orthree-dimensional data demultiplexing device or three-dimensional datadecoding device) performs the process shown in FIG. 31.

The three-dimensional data acquisition device (which includes firstdemultiplexer 4720, second demultiplexer 4740, or third demultiplexer4760, for example) acquires a file (an ISOBMFF file, for example) thatstores one or more units (NAL units, for example) that store an encodedstream, which is encoded point cloud data (S4791). The three-dimensionaldata acquisition device acquires the one or more units from the file(S4792). The control information (ftyp, for example) for the fileincludes information indicating that the data stored in the file isencoded point cloud data (pcc1, pcc2, or pcc3, for example).

For example, the three-dimensional data acquisition device determineswhether the data stored in the file is encoded point cloud data or notby referring to the information. When the three-dimensional dataacquisition device determines that the data stored in the file isencoded point cloud data, the three-dimensional data acquisition devicegenerates point cloud data by decoding the encoded point cloud dataincluded in the one or more units. Alternatively, when thethree-dimensional data acquisition device determines that the datastored in the file is encoded point cloud data, the three-dimensionaldata acquisition device outputs information indicating that the dataincluded in the one or more units is encoded point cloud data to aprocessor in a subsequent stage (first decoder 4640, second decoder4660, or decoder 4680, for example) (or notifies a processor in asubsequent stage that the data included in the one or more units isencoded point cloud data).

With such a configuration, the three-dimensional data acquisition devicecan quickly determine whether the data stored in the file is encodedpoint cloud data or not by referring to the control information for thefile. Therefore, the processing amount of the three-dimensional dataacquisition device or a device in a subsequent stage can be reduced, orthe processing speed of the three-dimensional data acquisition device ora device in a subsequent stage can be increased.

For example, the information represents the encoding method used for theencoding among the first encoding method and the second encoding method.Note that the fact that the data stored in the file is encoded pointcloud data and the encoding method used for the encoding of the pointcloud data among the first encoding method and the second encodingmethod may be indicated by a single piece of information or differentpieces of information.

With such a configuration, the three-dimensional data acquisition devicecan quickly determine the codec used for the data stored in the file byreferring to the control information for the file. Therefore, theprocessing amount of the three-dimensional data acquisition device or adevice in a subsequent stage can be reduced, or the processing speed ofthe three-dimensional data acquisition device or a device in asubsequent stage can be increased.

For example, based on the information, the three-dimensional dataacquisition device acquires the data encoded in any one of the firstencoding method and the second encoding method from the encoded pointcloud data including the data encoded in the first encoding method andthe data encoded in the second encoding method.

For example, the first encoding method is a method (GPCC) that encodesgeometry information that represents the position of point cloud data asan N-ary tree (N represents an integer equal to or greater than 2) andencodes attribute information using the geometry information, and thesecond encoding method is a method (VPCC) that generates atwo-dimensional image from point cloud data and encodes thetwo-dimensional image in a video encoding method.

For example, the file described above is in conformity with ISOBMFF(ISO-based media file format).

For example, the three-dimensional data acquisition device includes aprocessor and a memory, and the processor performs the processesdescribed above using the memory.

Embodiment 4

In this embodiment, types of the encoded data (geometry information(geometry), attribute information (attribute), and additionalinformation (metadata)) generated by first encoder 4630 or secondencoder 4650 described above, a method of generating additionalinformation (metadata), and a multiplexing process in the multiplexerwill be described. The additional information (metadata) may be referredto as a parameter set or control information (signaling information).

In this embodiment, the dynamic object (three-dimensional point clouddata that varies with time) described above with reference to FIG. 4will be described, for example. However, the same method can also beused for the static object (three-dimensional point cloud dataassociated with an arbitrary time point).

FIG. 32 is a diagram showing configurations of encoder 4801 andmultiplexer 4802 in a three-dimensional data encoding device accordingto this embodiment. Encoder 4801 corresponds to first encoder 4630 orsecond encoder 4650 described above, for example. Multiplexer 4802corresponds to multiplexer 4634 or 4656 described above.

Encoder 4801 encodes a plurality of PCC (point cloud compression) framesof point cloud data to generate a plurality of pieces of encoded data(multiple compressed data) of geometry information, attributeinformation, and additional information.

Multiplexer 4802 integrates a plurality of types of data (geometryinformation, attribute information, and additional information) into aNAL unit, thereby converting the data into a data configuration thattakes data access in the decoding device into consideration.

FIG. 33 is a diagram showing a configuration example of the encoded datagenerated by encoder 4801. Arrows in the drawing indicate a dependenceinvolved in decoding of the encoded data. The source of an arrow dependson data of the destination of the arrow. That is, the decoding devicedecodes the data of the destination of an arrow, and decodes the data ofthe source of the arrow using the decoded data. In other words, “a firstentity depends on a second entity” means that data of the second entityis referred to (used) in processing (encoding, decoding, or the like) ofdata of the first entity.

First, a process of generating encoded data of geometry information willbe described. Encoder 4801 encodes geometry information of each frame togenerate encoded geometry data (compressed geometry data) for eachframe. The encoded geometry data is denoted by G(i). i denotes a framenumber or a time point of a frame, for example.

Furthermore, encoder 4801 generates a geometry parameter set (GPS(i))for each frame. The geometry parameter set includes a parameter that canbe used for decoding of the encoded geometry data. The encoded geometrydata for each frame depends on an associated geometry parameter set.

The encoded geometry data formed by a plurality of frames is defined asa geometry sequence. Encoder 4801 generates a geometry sequenceparameter set (referred to also as geometry sequence PS or geometry SPS)that stores a parameter commonly used for a decoding process for theplurality of frames in the geometry sequence. The geometry sequencedepends on the geometry SPS.

Next, a process of generating encoded data of attribute information willbe described. Encoder 4801 encodes attribute information of each frameto generate encoded attribute data (compressed attribute data) for eachframe. The encoded attribute data is denoted by A(i). FIG. 33 shows anexample in which there are attribute X and attribute Y, and encodedattribute data for attribute X is denoted by AX(i), and encodedattribute data for attribute Y is denoted by AY(i).

Furthermore, encoder 4801 generates an attribute parameter set (APS(i))for each frame. The attribute parameter set for attribute X is denotedby AXPS(i), and the attribute parameter set for attribute Y is denotedby AYPS(i). The attribute parameter set includes a parameter that can beused for decoding of the encoded attribute information. The encodedattribute data depends on an associated attribute parameter set.

The encoded attribute data formed by a plurality of frames is defined asan attribute sequence. Encoder 4801 generates an attribute sequenceparameter set (referred to also as attribute sequence PS or attributeSPS) that stores a parameter commonly used for a decoding process forthe plurality of frames in the attribute sequence. The attributesequence depends on the attribute SPS.

In the first encoding method, the encoded attribute data depends on theencoded geometry data.

FIG. 33 shows an example in which there are two types of attributeinformation (attribute X and attribute Y). When there are two types ofattribute information, for example, two encoders generate data andmetadata for the two types of attribute information. For example, anattribute sequence is defined for each type of attribute information,and an attribute SPS is generated for each type of attributeinformation.

Note that, although FIG. 33 shows an example in which there is one typeof geometry information, and there are two types of attributeinformation, the present invention is not limited thereto. There may beone type of attribute information or three or more types of attributeinformation. In such cases, encoded data can be generated in the samemanner. If the point cloud data has no attribute information, there maybe no attribute information. In such a case, encoder 4801 does not haveto generate a parameter set associated with attribute information.

Next, a process of generating encoded data of additional information(metadata) will be described. Encoder 4801 generates a PCC stream PS(referred to also as PCC stream PS or stream PS), which is a parameterset for the entire PCC stream. Encoder 4801 stores a parameter that canbe commonly used for a decoding process for one or more geometrysequences and one or more attribute sequences in the stream PS. Forexample, the stream PS includes identification information indicatingthe codec for the point cloud data and information indicating analgorithm used for the encoding, for example. The geometry sequence andthe attribute sequence depend on the stream PS.

Next, an access unit and a GOF will be described. In this embodiment,concepts of access unit (AU) and group of frames (GOF) are newlyintroduced.

An access unit is a basic unit for accessing data in decoding, and isformed by one or more pieces of data and one or more pieces of metadata.For example, an access unit is formed by geometry information and one ormore pieces of attribute information associated with a same time point.A GOF is a random access unit, and is formed by one or more accessunits.

Encoder 4801 generates an access unit header (AU header) asidentification information indicating the top of an access unit. Encoder4801 stores a parameter relating to the access unit in the access unitheader. For example, the access unit header includes a configuration ofor information on the encoded data included in the access unit. Theaccess unit header further includes a parameter commonly used for thedata included in the access unit, such as a parameter relating todecoding of the encoded data.

Note that encoder 4801 may generate an access unit delimiter thatincludes no parameter relating to the access unit, instead of the accessunit header. The access unit delimiter is used as identificationinformation indicating the top of the access unit. The decoding deviceidentifies the top of the access unit by detecting the access unitheader or the access unit delimiter.

Next, generation of identification information for the top of a GOF willbe described. As identification information indicating the top of a GOF,encoder 4801 generates a GOF header. Encoder 4801 stores a parameterrelating to the GOF in the GOF header. For example, the GOF headerincludes a configuration of or information on the encoded data includedin the GOF. The GOF header further includes a parameter commonly usedfor the data included in the GOF, such as a parameter relating todecoding of the encoded data.

Note that encoder 4801 may generate a GOF delimiter that includes noparameter relating to the GOF, instead of the GOF header. The GOFdelimiter is used as identification information indicating the top ofthe GOF. The decoding device identifies the top of the GOF by detectingthe GOF header or the GOF delimiter.

In the PCC-encoded data, the access unit is defined as a PCC frame unit,for example. The decoding device accesses a PCC frame based on theidentification information for the top of the access unit.

For example, the GOF is defined as one random access unit. The decodingdevice accesses a random access unit based on the identificationinformation for the top of the GOF. For example, if PCC frames areindependent from each other and can be separately decoded, a PCC framecan be defined as a random access unit.

Note that two or more PCC frames may be assigned to one access unit, anda plurality of random access units may be assigned to one GOF.

Encoder 4801 may define and generate a parameter set or metadata otherthan those described above. For example, encoder 4801 may generatesupplemental enhancement information (SEI) that stores a parameter (anoptional parameter) that is not always used for decoding.

Next, a configuration of encoded data and a method of storing encodeddata in a NAL unit will be described.

For example, a data format is defined for each type of encoded data.FIG. 34 is a diagram showing an example of encoded data and a NAL unit.

For example, as shown in FIG. 34, encoded data includes a header and apayload. The encoded data may include length information indicating thelength (data amount) of the encoded data, the header, or the payload.The encoded data may include no header.

The header includes identification information for identifying the data,for example. The identification information indicates a data type or aframe number, for example.

The header includes identification information indicating a referencerelationship, for example. The identification information is stored inthe header when there is a dependence relationship between data, forexample, and allows an entity to refer to another entity. For example,the header of the entity to be referred to includes identificationinformation for identifying the data. The header of the referring entityincludes identification information indicating the entity to be referredto.

Note that, when the entity to be referred to or the referring entity canbe identified or determined from other information, the identificationinformation for identifying the data or identification informationindicating the reference relationship can be omitted.

Multiplexer 4802 stores the encoded data in the payload of the NAL unit.The NAL unit header includes pcc_nal_unit_type, which is identificationinformation for the encoded data. FIG. 35 is a diagram showing asemantics example of pcc_nal_unit_type.

As shown in FIG. 35, when pcc_codec_type is codec 1 (Codec1: firstencoding method), values 0 to 10 of pcc_nal_unit_type are assigned toencoded geometry data (Geometry), encoded attribute X data (AttributeX),encoded attribute Y data (AttributeY), geometry PS (Geom. PS), attributeXPS (AttrX. S), attribute YPS (AttrY. PS), geometry SPS (GeometrySequence PS), attribute X SPS (AttributeX Sequence PS), attribute Y SPS(AttributeY Sequence PS), AU header (AU Header), and GOF header (GOFHeader) in codec 1. Values of 11 and greater are reserved in codec 1.

When pcc_codec_type is codec 2 (Codec2: second encoding method), valuesof 0 to 2 of pcc_nal_unit_type are assigned to data A (DataA), metadataA (MetaDataA), and metadata B (MetaDataB) in the codec. Values of 3 andgreater are reserved in codec 2.

Next, an order of transmission of data will be described. In thefollowing, restrictions on the order of transmission of NAL units willbe described.

Multiplexer 4802 transmits NAL units on a GOF basis or on an AU basis.Multiplexer 4802 arranges the GOF header at the top of a GOF, andarranges the AU header at the top of an AU.

In order to allow the decoding device to decode the next AU and thefollowing AUs even when data is lost because of a packet loss or thelike, multiplexer 4802 may arrange a sequence parameter set (SPS) ineach AU.

When there is a dependence relationship for decoding between encodeddata, the decoding device decodes the data of the entity to be referredto and then decodes the data of the referring entity. In order to allowthe decoding device to perform decoding in the order of receptionwithout rearranging the data, multiplexer 4802 first transmits the dataof the entity to be referred to.

FIG. 36 is a diagram showing examples of the order of transmission ofNAL units. FIG. 36 shows three examples, that is, geometryinformation-first order, parameter-first order, and data-integratedorder.

The geometry information-first order of transmission is an example inwhich information relating to geometry information is transmittedtogether, and information relating to attribute information istransmitted together. In the case of this order of transmission, thetransmission of the information relating to the geometry informationends earlier than the transmission of the information relating to theattribute information.

For example, according to this order of transmission is used, when thedecoding device does not decode attribute information, the decodingdevice may be able to have an idle time since the decoding device canomit decoding of attribute information. When the decoding device isrequired to decode geometry information early, the decoding device maybe able to decode geometry information earlier since the decoding deviceobtains encoded data of the geometry information earlier.

Note that, although in FIG. 36 the attribute X SPS and the attribute YSPS are integrated and shown as the attribute SPS, the attribute X SPSand the attribute Y SPS may be separately arranged.

In the parameter set-first order of transmission, a parameter set isfirst transmitted, and data is then transmitted.

As described above, as far as the restrictions on the order oftransmission of NAL units are met, multiplexer 4802 can transmit NALunits in any order. For example, order identification information may bedefined, and multiplexer 4802 may have a function of transmitting NALunits in a plurality of orders. For example, the order identificationinformation for NAL units is stored in the stream PS.

The three-dimensional data decoding device may perform decoding based onthe order identification information. The three-dimensional datadecoding device may indicate a desired order of transmission to thethree-dimensional data encoding device, and the three-dimensional dataencoding device (multiplexer 4802) may control the order of transmissionaccording to the indicated order of transmission.

Note that multiplexer 4802 can generate encoded data having a pluralityof functions merged to each other as in the case of the data-integratedorder of transmission, as far as the restrictions on the order oftransmission are met. For example, as shown in FIG. 36, the GOF headerand the AU header may be integrated, or AXPS and AYPS may be integrated.In such a case, an identifier that indicates data having a plurality offunctions is defined in pcc_nal_unit_type.

In the following, variations of this embodiment will be described. Thereare levels of PSs, such as a frame-level PS, a sequence-level PS, and aPCC sequence-level PS. Provided that the PCC sequence level is a higherlevel, and the frame level is a lower level, parameters can be stored inthe manner described below.

The value of a default PS is indicated in a PS at a higher level. If thevalue of a PS at a lower level differs from the value of the PS at ahigher level, the value of the PS is indicated in the PS at the lowerlevel. Alternatively, the value of the PS is not described in the PS atthe higher level but is described in the PS at the lower level.Alternatively, information indicating whether the value of the PS isindicated in the PS at the lower level, at the higher level, or at boththe levels is indicated in both or one of the PS at the lower level andthe PS at the higher level. Alternatively, the PS at the lower level maybe merged with the PS at the higher level. If the PS at the lower leveland the PS at the higher level overlap with each other, multiplexer 4802may omit transmission of one of the PSs.

Note that encoder 4801 or multiplexer 4802 may divide data into slicesor tiles and transmit each of the divided slices or tiles as divideddata. The divided data includes information for identifying the divideddata, and a parameter used for decoding of the divided data is includedin the parameter set. In this case, an identifier that indicates thatthe data is data relating to a tile or slice or data storing a parameteris defined in pcc_nal_unit_type.

Embodiment 5

Hereinafter, the dividing method for point cloud data will be described.FIG. 37 is a diagram illustrating an example of slice and tile dividing.

First, the method for slice dividing will be described. Thethree-dimensional data encoding device divides three-dimensional pointcloud data into arbitrary point clouds on a slice-by-slice basis. Inslice dividing, the three-dimensional data encoding device does notdivide the geometry information and the attribute informationconstituting points, but collectively divides the geometry informationand the attribute information. That is, the three-dimensional dataencoding device performs slice dividing so that the geometry informationand the attribute information of an arbitrary point belong to the sameslice. Note that, as long as these are followed, the number of divisionsand the dividing method may be any number and any method. Furthermore,the minimum unit of division is a point. For example, the numbers ofdivisions of geometry information and attribute information are thesame. For example, a three-dimensional point corresponding to geometryinformation after slice dividing, and a three-dimensional pointcorresponding to attribute information are included in the same slice.

Also, the three-dimensional data encoding device generates sliceadditional information, which is additional information related to thenumber of divisions and the dividing method at the time of slicedividing. The slice additional information is the same for geometryinformation and attribute information. For example, the slice additionalinformation includes the information indicating the reference coordinateposition, size, or side length of a bounding box after division. Also,the slice additional information includes the information indicating thenumber of divisions, the division type, etc.

Next, the method for tile dividing will be described. Thethree-dimensional data encoding device divides the data divided intoslices into slice geometry information (G slice) and slice attributeinformation (A slice), and divides each of the slice geometryinformation and the slice attribute information on a tile-by-tile basis.

Note that, although FIG. 37 illustrates the example in which division isperformed with an octree structure, the number of divisions and thedividing method may be any number and any method.

Also, the three-dimensional data encoding device may divide geometryinformation and attribute information with different dividing methods,or may divide geometry information and attribute information with thesame dividing method. Additionally, the three-dimensional data encodingdevice may divide a plurality of slices into tiles with differentdividing methods, or may divide a plurality of slices into tiles withthe same dividing method.

Furthermore, the three-dimensional data encoding device generates tileadditional information related to the number of divisions and thedividing method at the time of tile dividing. The tile additionalinformation (geometry tile additional information and attribute tileadditional information) is separate for geometry information andattribute information. For example, the tile additional informationincludes the information indicating the reference coordinate position,size, or side length of a bounding box after division. Additionally, thetile additional information includes the information indicating thenumber of divisions, the division type, etc.

Next, an example of the method of dividing point cloud data into slicesor tiles will be described. As the method for slice or tile dividing,the three-dimensional data encoding device may use a predeterminedmethod, or may adaptively switch methods to be used according to pointcloud data.

At the time of slice dividing, the three-dimensional data encodingdevice divides a three-dimensional space by collectively handlinggeometry information and attribute information. For example, thethree-dimensional data encoding device determines the shape of anobject, and divides a three-dimensional space into slices according tothe shape of the object. For example, the three-dimensional dataencoding device extracts objects such as trees or buildings, andperforms division on an object-by-object basis. For example, thethree-dimensional data encoding device performs slice dividing so thatthe entirety of one or a plurality of objects are included in one slice.Alternatively, the three-dimensional data encoding device divides oneobject into a plurality of slices.

In this case, the encoding device may change the encoding method foreach slice, for example. For example, the encoding device may use ahigh-quality compression method for a specific object or a specific partof the object. In this case, the encoding device may store theinformation indicating the encoding method for each slice in additionalinformation (metadata).

Also, the three-dimensional data encoding device may perform slicedividing so that each slice corresponds to a predetermined coordinatespace based on map information or geometry information.

At the time of tile dividing, the three-dimensional data encoding deviceseparately divides geometry information and attribute information. Forexample, the three-dimensional data encoding device divides slices intotiles according to the data amount or the processing amount. Forexample, the three-dimensional data encoding device determines whetherthe data amount of a slice (for example, the number of three-dimensionalpoints included in a slice) is greater than a predetermined thresholdvalue. When the data amount of the slice is greater than the thresholdvalue, the three-dimensional data encoding device divides slices intotiles. When the data amount of the slice is less than the thresholdvalue, the three-dimensional data encoding device does not divide slicesinto tiles.

For example, the three-dimensional data encoding device divides slicesinto tiles so that the processing amount or processing time in thedecoding device is within a certain range (equal to or less than apredetermined value). Accordingly, the processing amount per tile in thedecoding device becomes constant, and distributed processing in thedecoding device becomes easy.

Additionally, when the processing amount is different between geometryinformation and attribute information, for example, when the processingamount of geometry information is greater than the processing amount ofattribute information, the three-dimensional data encoding device makesthe number of divisions of geometry information larger than the numberof divisions of attribute information.

Furthermore, for example, when geometry information may be decoded anddisplayed earlier, and attribute information may be slowly decoded anddisplayed later in the decoding device according to contents, thethree-dimensional data encoding device may make the number of divisionsof geometry information larger than the number of divisions of attributeinformation. Accordingly, since the decoding device can increase theparallel number of geometry information, it is possible to make theprocessing of geometry information faster than the processing ofattribute information.

Note that the decoding device does not necessarily have to processsliced or tiled data in parallel, and may determine whether or not toprocess them in parallel according to the number or capability ofdecoding processors.

By performing division with the method as described above, it ispossible to achieve adaptive encoding according to contents or objects.Also, parallel processing in decoding processing can be achieved.Accordingly, the flexibility of a point cloud encoding system or a pointcloud decoding system is improved.

FIG. 38 is a diagram illustrating dividing pattern examples of slicesand tiles. DU in the diagram is a data unit (DataUnit), and indicatesthe data of a tile or a slice. Additionally, each DU includes a sliceindex (SliceIndex) and a tile index (TileIndex). The top right numericalvalue of a DU in the diagram indicates the slice index, and the bottomleft numerical value of the DU indicates the tile index.

In Pattern 1, in slice dividing, the number of divisions and thedividing method are the same for G slice and A slice. In tile dividing,the number of divisions and the dividing method for G slice aredifferent from the number of divisions and the dividing method for Aslice. Additionally, the same number of divisions and dividing methodare used among a plurality of G slices. The same number of divisions anddividing method are used among a plurality of A slices.

In Pattern 2, in slice dividing, the number of divisions and thedividing method are the same for G slice and A slice. In tile dividing,the number of divisions and the dividing method for G slice aredifferent from the number of divisions and the dividing method for Aslice. Additionally, the number of divisions and the dividing method aredifferent among a plurality of G slices. The number of divisions and thedividing method are different among a plurality of A slices.

Embodiment 6

Hereinafter, an example of performing slice division after tile divisionwill be described. An autonomous application for automated driving of avehicle etc. requires not point cloud data of all areas but point clouddata of an area surrounding a vehicle or an area in a travelingdirection of a vehicle. Here, tiles and slices can be used toselectively decode original point cloud data. It is possible to achievethe improvement of coding efficiency or parallel processing by dividingthree-dimensional point cloud data into tiles and further dividing thetiles into slices. When data is divided, additional information(metadata) is generated, and the generated additional information istransmitted to a multiplexer.

FIG. 39 is a block diagram illustrating a configuration of first encoder5010 included in a three-dimensional data encoding device according tothe present embodiment. First encoder 5010 generates encoded data(encoded stream) by encoding point cloud data using a first encodingmethod (geometry based PCC (GPCC)). First encoder 5010 includes divider5011, geometry information encoders 5012, attribute information encoders5013, additional information encoder 5014, and multiplexer 5015.

Divider 5011 generates pieces of divided data by dividing point clouddata. Specifically, divider 5011 generates pieces of divided data bydividing a space of point cloud data into subspaces. Here, a subspace isone of a tile and a slice, or a combination of a tile and a slice. Morespecifically, point cloud data includes geometry information, attributeinformation, and additional information. Divider 5011 divides geometryinformation into pieces of divided geometry information and attributeinformation into pieces of divided attribute information. In addition,divider 5011 generates additional information regarding division.

For example, first, divider 5011 divides a point cloud into tiles. Next,divider 5011 further divides the obtained tiles into slices.

Geometry information encoders 5012 generate pieces of encoded geometryinformation by encoding pieces of divided geometry information. Forexample, geometry information encoders 5012 process pieces of dividedgeometry information in parallel.

Attribute information encoders 5013 generate pieces of encoded attributeinformation by encoding pieces of divided attribute information. Forexample, attribute information encoders 5013 process pieces of dividedgeometry information in parallel.

Additional information encoder 5014 generates encoded additionalinformation by encoding additional information included in point clouddata and additional information regarding data division generated at thetime of dividing by divider 5011.

Multiplexer 5015 generates encoded data (encoded stream) by multiplexingpieces of encoded geometry information, pieces of encoded attributeinformation, and encoded additional information, and transmits thegenerated encoded data. The encoded additional information is also usedat the time of decoding.

It should be noted that although FIG. 39 shows two geometry informationencoders 5012 and two attribute information encoders 5013 as an example,the number of geometry information encoders 5012 and the number ofattribute information encoders 5013 may be one or at least three.Moreover, pieces of divided data may be processed in parallel inidentical chips, such as cores in a CPU, in a core of each of chips, orin cores of each of chips.

The following describes a decoding process. FIG. 40 is a block diagramillustrating a configuration of first decoder 5020. First decoder 5020restores point cloud data by decoding encoded data (encoded stream)generated by encoding the point cloud data using the first encodingmethod (GPCC). First decoder 5020 includes demultiplexer 5021, geometryinformation decoders 5022, attribute information decoders 5023,additional information decoder 5024, and combiner 5025.

Demultiplexer 5021 generates pieces of encoded geometry information,pieces of encoded attribute information, and encoded additionalinformation by demultiplexing encoded data (encoded stream).

Geometry information decoders 5022 generate pieces of divided geometryinformation by decoding pieces of encoded geometry information. Forexample, geometry information decoders 5022 process pieces of encodedgeometry information in parallel.

Attribute information decoders 5023 generate pieces of divided attributeinformation by decoding pieces of encoded attribute information. Forexample, attribute information decoders 5023 process pieces of encodedattribute information in parallel.

Additional information decoder 5024 generates additional information bydecoding encoded additional information.

Combiner 5025 generates geometry information by combining pieces ofdivided geometry information using additional information. Combiner 5025also generates attribute information by combining pieces of dividedattribute information using additional information. For example, first,combiner 5025 generates pieces of point cloud data corresponding totiles by combing pieces of decoded point cloud data corresponding toslices using slice additional information. Next, combiner 5025 restoresoriginal point cloud data by combining pieces of point cloud datacorresponding to the tiles using tile additional information.

It should be noted that although FIG. 39 shows two geometry informationdecoders 5022 and two attribute information decoders 5023 as an example,the number of geometry information decoders 5022 and the number ofattribute information decoders 5023 may be one or at least three.Moreover, pieces of divided data may be processed in parallel inidentical chips, such as cores in a CPU, in a core of each of chips, orin cores of each of chips.

The following describes a method of dividing point cloud data. Anautonomous application for automated driving of a vehicle etc. requiresnot point cloud data of all areas but point cloud data of an areasurrounding a vehicle or an area in a traveling direction of a vehicle.

FIG. 41 is a diagram illustrating examples of a tile shape. As shown inFIG. 41, examples of the tile shape may include various shapes such as acircle, a rectangle, or an ellipse.

FIG. 42 is a diagram illustrating an example of tiles and slices. Acomposition of slices may differ between tiles. For example, acomposition of tiles or slices may be optimized based on a data volume.Alternatively, a composition of tiles or slices may be optimized basedon decoding speed.

Tile division may be performed based on geometry information. In thiscase, attribute information is divided in the same manner ascorresponding geometry information.

Moreover, in slice division after tile division, geometry informationand attribute information may be divided into slices using differentmethods. For example, a slice division method in each tile may beselected upon request from an application. A different slice divisionmethod or a different tile division method may be used based on arequest from an application.

For example, divider 5011 divides three-dimensional point cloud datainto one or more tiles in a two-dimensional shape obtained by seeing thethree-dimensional point cloud data from top, based on positioninformation such as map information. Divider 5011 divides each of theone or more tiles into one or more slices afterward.

It should be noted that divider 5011 may divide geometry information(geometry) and attribute information (attribute) into slices using thesame method.

It should be noted that each of geometry information and attributeinformation may be of one type or two or more types. In addition, whenpoint cloud data has no attribute information, attribute information maybe unnecessary.

FIG. 43 is a block diagram of divider 5011. Divider 5011 includes tiledivider 5031, geometry information slice divider (geometry slicedivider) 5032, and attribute information slice divider (attribute slicedivider) 5033.

Tile divider 5031 generates pieces of tile geometry information bydividing geometry information (position (geometry)) into tiles. Inaddition, tile divider 5031 generates pieces of tile attributeinformation by dividing attribute information (attribute) into tiles.Additionally, tile divider 5031 outputs tile additional information(tile metadata) including information regarding tile division andinformation generated in the tile division.

Geometry information slice divider 5032 generates pieces of dividedgeometry information (pieces of slice geometry information) by dividingpieces of tile geometry information into slices. In addition, geometryinformation slice divider 5032 outputs geometry slice additionalinformation (geometry slice metadata) including information regardingslice division of geometry information and information generated in theslice division of the geometry information.

Attribute information slice divider 5033 generates pieces of dividedattribute information (pieces of slice attribute information) bydividing pieces of tile attribute information into slices. In addition,attribute information slice divider 5033 outputs attribute sliceadditional information (attribute slice metadata) including informationregarding slice division of attribute information and informationgenerated in the slice division of the attribute information.

The following describes examples of a tile shape. An entirethree-dimensional map (3D map) is divided into tiles. Data of the tilesare selectively transmitted to a three-dimensional data decoding device.Alternatively, the data of the tiles are transmitted to thethree-dimensional data decoding device in decreasing order ofimportance. A tile shape may be selected from shapes according to asituation.

FIG. 44 is a diagram illustrating an example of a map in a top of viewof point cloud data obtained by LiDAR. The example shown in FIG. 44 ispoint cloud data of a highway and includes an overpass (flyover).

FIG. 45 is a diagram illustrating an example of dividing the point clouddata shown in FIG. 44 into square tiles. It is easy to make such adivision into squares in a map server. For a normal road, the height ofa tile is set low. The height of tiles is set higher for an overpassthan for the normal road so that the tiles contain the overpass.

FIG. 46 is a diagram illustrating an example of dividing the point clouddata shown in FIG. 44 into circular tiles. In this case, neighboringtiles may overlap each other in plan view. When a vehicle requires pointcloud data of a surrounding area, the three-dimensional data encodingdevice transmits, to the vehicle, point cloud data of an area includingcolumns (circles in top view) surrounding the vehicle.

As with the example shown in FIG. 45, for a normal road, the height of atile is set low. The height of tiles is set higher for an overpass thanfor the normal road so that the tiles contain the overpass.

The three-dimensional data encoding device may change the height of atile according to, for example, the shape or height of a road orbuilding. In addition, the three-dimensional data encoding device maychange the height of a tile according to position information or areainformation. Additionally, the three-dimensional data encoding devicemay change the height of each tile. Alternatively, the three-dimensionaldata encoding device may change the height of tiles for each zoneincluding the tiles. To put it another way, the three-dimensional dataencoding device may set tiles in a zone to the same height. Moreover,tiles having different heights may overlap each other in top view.

FIG. 47 is a diagram illustrating an example of tile division when tileshaving various shapes, sizes, and heights are used. Any tile may haveany shape or size, or a combination of these.

For example, in addition to making a division into non-overlappingsquare tiles and making a division into overlapping circular tiles asdescribed above, the three-dimensional data encoding device may make adivision into overlapping square tiles. Moreover, the tile shape neednot be a square or a circle, and may be a polygon having three or morevertices, or a shape having no vertices.

Furthermore, a tile shape may be of two or more types, and tiles havingdifferent shapes may overlap each other. In addition, a tile shape maybe of one or more types; and when the same shape is used for dividedtiles, the same shape may include shapes different in size or suchshapes may overlap each other.

For example, a tile to be used is larger for an area including no objectsuch as a road than for an area including an object. Moreover, thethree-dimensional data encoding device may adaptively change a tileshape or size according to an object.

Furthermore, for example, the three-dimensional data encoding device mayset tiles in a traveling direction of an automobile (a vehicle) to alarge size because reading of tiles at a great distance ahead of theautomobile in the traveling direction is likely to be needed; and settiles in a side lateral to the automobile to a smaller size than thetiles in the traveling direction because the automobile is less likelyto move to the side.

FIG. 48 is a diagram illustrating an example of data of tiles stored ina server. For example, point cloud data is divided into tiles andencoded in advance, and the obtained encoded data is stored in a server.A user obtains the data of desired tiles from the server when necessary.Alternatively, the server (the three-dimensional data encoding device)may perform tile division and encoding so that tiles include datadesired by the user, in response to an instruction from the user.

For example, when a movable body (a vehicle) travels at a high speed, itis conceivable that more extensive point cloud data is needed. For thisreason, the server may determine a tile shape and size based on apre-estimated vehicular speed (e.g., a legal speed on a road, avehicular speed estimated from the width or shape of a road, or astatistical vehicular speed), and perform tile division. Alternatively,as shown in FIG. 48, the server may encode tiles having a shape or sizein advance, and store the obtained data. The movable body may obtaindata of tiles having an appropriate shape or size according to thetraveling direction and speed of the movable body.

FIG. 49 is a diagram illustrating an example of a system regarding tiledivision. As shown in FIG. 49, a tile shape and an area may bedetermined based on the location of an antenna (a base station) that isa means of communication transmitting point cloud data, or on acommunication area supported by an antenna. Alternatively, when pointcloud data is generated by a sensor such as a camera, a tile shape andan area may be determined based on the location or a target range (adetection range) of the sensor.

One tile may be assigned to one antenna or one sensor, or one tile maybe assigned to antennas or sensors. In addition, tiles may be assignedto one antenna or one sensor. An antenna or a sensor may be fixed ormovable.

For example, encoded data divided into tiles may be managed by a serverconnected to an antenna or a sensor for an area assigned to the tiles.The server may manage the encoded data of the area and tile informationof a neighboring area. Pieces of encoded data of tiles may be managed ina centralized server (a cloud) that manages servers each correspondingto a different one of the tiles. Alternatively, instead of providing theservers each corresponding to the different one of the tiles, antennasor sensors may be directly connected to the centralized server.

It should be noted that the target range of an antenna or a sensor maychange depending on the power of radio waves, differences betweendevices, and installation conditions, and a tile shape and size maychange in conformity with these. Instead of a tile, a slice or a PCCframe may be assigned based on the target range of the antenna or thesensor.

The following describes a method of dividing a tile into slices. It ispossible to improve the coding efficiency by assigning similar objectsto the same slice.

For example, the three-dimensional data encoding device may recognizeobjects (e.g., a road, a building, a tree) using features of point clouddata, and perform slice division by clustering point clouds for each ofthe objects.

Alternatively, the three-dimensional data encoding device may classifyobjects having the same attribute into groups, and perform slicedivision by assigning a slice to each of the groups. Here, an attributeis, for example, information regarding motion. Objects are classifiedinto groups according to dynamic information about pedestrians, cars,etc., quasi-dynamic information about accidents, congestion, etc.,quasi-static information about traffic controls, roadwork, etc., andstatic information about road surfaces, structures, etc.

It should be noted that slices may have overlapping data. For example,when slice division is performed for each object group, any object maybelong to one object group or two or more object groups.

FIG. 50 is a diagram illustrating an example of this slice division. Forexample, a tile is a cuboid in the example shown in FIG. 50. It shouldbe noted that a tile may be columnar or have another shape.

Point clouds included in a tile are classified into object groups suchas road, building, and tree. Then, slice division is performed so thateach object group is included in a different one of slices.Subsequently, the slices are encoded separately.

The following describes a method of encoding divided data. Thethree-dimensional data encoding device (first encoder 5010) encodes eachdivided data. When the three-dimensional data encoding device encodesattribute information, the three-dimensional data encoding devicegenerates, as additional information, dependency relationshipinformation indicating based on which composition information (geometryinformation, additional information, or another attribute information)encoding has been performed. In other words, dependency relationshipinformation indicates, for example, composition information of areference destination (a dependee). In this case, the three-dimensionaldata encoding device generates dependency relationship information basedon composition information corresponding to a divided shape forattribute information. It should be noted that the three-dimensionaldata encoding device may generate dependency relationship informationbased on composition information corresponding to divided shapes.

Dependency relationship information may be generated by thethree-dimensional data encoding device, and the generated dependencyrelationship information may be transmitted to the three-dimensionaldata decoding device. Alternatively, the three-dimensional data decodingdevice may generate dependency relationship information, and thethree-dimensional data encoding device need not transmit dependencyrelationship information. In addition, a dependency relationship to beused by the three-dimensional data encoding device may be determined inadvance, and the three-dimensional data encoding device need nottransmit dependency relationship information.

FIG. 51 is a diagram illustrating an example of a dependencyrelationship of each data. The pointed end of an arrow in the figureindicates a dependee, and the other end of the arrow indicates adepender. The three-dimensional data decoding device decodes data inorder from dependee to depender. Data indicated by a solid line in thefigure is data actually transmitted, and data indicated by a broken lineis data not transmitted.

In the figure, G denotes geometry information, and A denotes attributeinformation. G_(t1) denotes geometry information for tile number 1, andG_(t2) denotes geometry information for tile number 2. G_(t1s1) denotesgeometry information for tile number 1 and slice number 1, G_(t1s2)denotes geometry information for tile number 1 and slice number 2,G_(t2s1) denotes geometry information for tile number 2 and slice number1, and G_(t2s2) denotes geometry information for tile number 2 and slicenumber 2. Likewise, A_(t1) denotes attribute information for tile number1, and A_(t2) denotes attribute information for tile number 2. A_(t1s1)denotes attribute information for tile number 1 and slice number 1,A_(t1s2) denotes attribute information for tile number 1 and slicenumber 2, A_(t2s1) denotes attribute information for tile number 2 andslice number 1, and A_(t2s2) denotes attribute information for tilenumber 2 and slice number 2.

Mtile denotes tile additional information, MGslice denotes geometryslice additional information, and MAslice denotes attribute sliceadditional information. D_(t1s1) denotes dependency relationshipinformation of attribute information A_(t1s1), and D_(t2s1) denotesdependency relationship information of attribute information A_(t2s1).

It should be noted that a different structure resulting from tiledivision or slice division may be used according to an application etc.

The three-dimensional data encoding device may rearrange data indecoding order so that the three-dimensional data decoding device neednot rearrange data. It should be noted that the three-dimensional datadecoding device may rearrange data, or both the three-dimensional dataencoding device and the three-dimensional data decoding device mayrearrange data.

FIG. 52 is a diagram illustrating an example of decoding order of data.In the example shown in FIG. 52, data are decoded in order from theleft. The three-dimensional data decoding device decodes, out of datahaving a dependency relationship with each other, data of a dependeefirst. For example, the three-dimensional data encoding devicerearranges data in this order and transmits the data. It should be notedthat any order may be used as long as data of a dependee takesprecedence. Moreover, the three-dimensional data encoding device maytransmit additional information and dependency relationship informationbefore data.

Furthermore, the three-dimensional data decoding device may selectivelydecode tiles based on a request from an application and informationobtained from a NAL unit header. FIG. 53 is a diagram illustrating anexample of encoded data of tiles. For example, decoding order of tilesis optional. In other words, tiles need not have a dependencyrelationship with each other.

The following describes a configuration of combiner 5025 included infirst decoder 5020. FIG. 54 is a block diagram illustrating aconfiguration of combiner 5025. Combiner 5025 includes geometryinformation slice combiner (geometry slice combiner) 5041, attributeinformation slice combiner (attribute slice combiner) 5042, and tilecombiner 5043.

Geometry information slice combiner 5041 generates pieces of tilegeometry information by combining pieces of divided geometry informationusing geometry slice additional information. Attribute information slicecombiner 5042 generates pieces of tile attribute information bycombining pieces of divided attribute information using attribute sliceadditional information.

Tile combiner 5043 generates geometry information by combining pieces oftile geometry information using tile additional information. Besides,tile combiner 5043 generates attribute information by combining piecesof tile attribute information using tile additional information.

It should be noted that the number of divided slices or tiles is atleast one. In other words, slice division or tile division need not beperformed.

The following describes a structure of encoded data subjected to slicedivision or tile division, and a method of storing encoded data in a NALunit (a multiplexing method). FIG. 55 is a diagram illustrating astructure of encoded data and a method of storing encoded data in a NALunit.

Encoded data (divided geometry information or divided attributeinformation) is stored in a NAL unit payload.

Encoded data includes a header and a payload. The header includesidentification information for identifying data included in the payload.Examples of the identification information include a type of slicedivision or tile division (slice_type, tile_type), index information foridentifying a slice or a tile (slice_idx, tile_idx), geometryinformation of data (a slice or tile), or an address of data (address).Index information for identifying a slice is also referred to as a sliceindex (SliceIndex). Index information for identifying a tile is alsoreferred to as a tile index (TileIndex). A division type indicates, forexample, a method based on an object shape as described above, a methodbased on map information or position information, or a method based on adata volume or an amount of processing.

Moreover, the header of the encoded data includes identificationinformation indicating a dependency relationship. To put it another way,when data have a dependency relationship with each other, the headerincludes identification information for a depender to refer to adependee. For example, the header of data of a dependee includesidentification information for identifying the data. The header of dataof a depender includes identification information indicating a dependee.It should be noted that when identification information for identifyingdata, additional information regarding slice division or tile division,and identification information indicating a dependency relationship areidentifiable or derivable from other information, these pieces ofinformation may be omitted.

The following describes procedures of a point cloud data encodingprocess and a point cloud data decoding process according to the presentembodiment. FIG. 56 is a flowchart of a point cloud data encodingprocess according to the present embodiment.

First, the three-dimensional data encoding device determines a divisionmethod to be used (S5011). Examples of the division method include tiledivision and slice division. A division method may include a divisionnumber, a division type, etc. when tile division or slice division isperformed. A division type indicates, for example, a method based on anobject shape as described above, a method based on map information orgeometry information, or a method based on a data volume or an amount ofprocessing. It should be noted that a division method may be determinedin advance.

When tile division is performed (YES in S5012), the three-dimensionaldata encoding device generates pieces of tile geometry information andpieces of tile attribute information by dividing geometry informationand attribute information collectively (S5013). Besides, thethree-dimensional data encoding device generates tile additionalinformation regarding the tile division. It should be noted that thethree-dimensional data encoding device may divide geometry informationand attribute information separately.

When slice division is performed (YES in S5014), the three-dimensionaldata encoding device generates pieces of divided geometry informationand pieces of divided attribute information by dividing the pieces oftile geometry information and the pieces of tile attribute information(or the geometry information and the attribute information) separately(S5015). Also, the three-dimensional data encoding device generatesgeometry slice additional information and attribute slice additionalinformation regarding the slice division. It should be noted that thethree-dimensional data encoding device may divide tile geometryinformation and tile attribute information collectively.

Next, the three-dimensional data encoding device generates pieces ofencoded geometry information and pieces of encoded attribute informationby respectively encoding the pieces of divided geometry information andthe pieces of divided attribute information (S5016). In addition, thethree-dimensional data encoding device generates dependency relationshipinformation.

Finally, the three-dimensional data encoding device generates encodeddata (an encoded stream) by storing in NAL units (multiplexing) thepieces of encoded geometry information, the pieces of encoded attributeinformation, and additional information (S5017). Additionally, thethree-dimensional data encoding device transmits the generated encodeddata.

FIG. 57 is a flowchart of a point cloud data decoding process accordingto the present embodiment. First, the three-dimensional data decodingdevice determines a division method by analyzing additional information(tile additional information, geometry slice additional information,attribute slice additional information) regarding a division methodincluded in encoded data (an encoded stream) (S5021). Examples of thedivision method include tile division and slice division. A divisionmethod may include a division number, a division type, etc. when tiledivision or slice division is performed.

Next, the three-dimensional data decoding device generates dividedgeometry information and divided attribute information by decodingpieces of encoded geometry information and pieces of encoded attributeinformation included in the encoded data, using dependency relationshipinformation included in the encoded data (S5022).

When the additional information indicates that slice division has beenperformed (YES in S5023), the three-dimensional data decoding devicegenerates pieces of tile geometry information and pieces of tileattribute information by combining pieces of divided geometryinformation and combining pieces of divided attribute information, usingrespective methods, based on the geometry slice additional informationand the attribute slice additional information (S5024). It should benoted that the three-dimensional data decoding device may combine thepieces of divided geometry information and combine the pieces of dividedattribute information, using the same method.

When the additional information indicates that tile division has beenperformed (YES in S5025), the three-dimensional data decoding devicegenerates geometry information and attribute information by combiningthe pieces of tile geometry information (the pieces of divided geometryinformation) and combining the pieces of tile attribute information (thepieces of divided attribute information), using the same method, basedon tile additional information (S5026). It should be noted that thethree-dimensional data decoding device may combine the pieces of tilegeometry information and combine the pieces of tile attributeinformation, using respective methods.

The following describes tile additional information. Thethree-dimensional data encoding device generates tile additionalinformation that is metadata regarding a tile division method, andtransmits the generated tile additional information to thethree-dimensional data decoding device.

FIG. 58 is a diagram illustrating an example of syntax of tileadditional information (TileMetaData). As shown in FIG. 58, for example,tile additional information includes division method information(type_of_divide), shape information (topview_shape), an overlap flag(tile_overlap_flag), overlap information (type_of_overlap), heightinformation (tile_height), a tile number (tile_number), and tileposition information (global_position, relative_position).

Division method information (type_of_divide) indicates a tile divisionmethod. For example, division method information indicates whether atile division method is division based on map information, that is,division based on top view (top_view) or another division (other).

Shape information (topview_shape) is included in tile additionalinformation when a tile division method is, for example, division basedon top view. Shape information indicates a shape in top view of a tile.Examples of the shape include a square and a circle. Moreover, theexamples of the shape may include an ellipse, a rectangle, or a polygonother than a quadrangle, or may include a shape other than these. Itshould be noted that shape information may indicate not only a shape intop view of a tile but also a three-dimensional shape (e.g., a cube, around column) of a tile.

An overlap flag (tile_overlap_flag) indicates whether tiles overlap eachother. For example, an overlap flag is included in tile additionalinformation when a tile division method is division based on top view.In this case, the overlap flag indicates whether tiles overlap eachother in top view. It should be noted that an overlap flag may indicatewhether tiles overlap each other in a three-dimensional space.

Overlap information (type_of_overlap) is included in tile additionalinformation when, for example, tiles overlap each other. Overlapinformation indicates, for example, how tiles overlap each other. Forexample, overlap information indicates the size of an overlappingregion.

Height information (tile_height) indicates the height of a tile. Itshould be noted that height information may include informationindicating a tile shape. For example, when the shape of a tile in topview is a rectangle, the information may indicate the length of a side(a vertical length, a horizontal length) of the rectangle. When theshape of a tile in top view is a circle, the information may indicatethe diameter or radius of the circle.

Moreover, height information may indicate the height of each tile or aheight common to tiles. In addition, height types such as roads andoverpasses may be set in advance, and height information may indicatethe height of each of the height types and a height type of each tile.Alternatively, a height of each height type may be specified in advance,and height information may indicate a height type of each tile. In otherwords, height information need not indicate a height of each heighttype.

A tile number (tile_number) indicates the number of tiles. It should benoted that tile additional information may include informationindicating an interval between tiles.

Tile position information (global_position, relative_position) isinformation for identifying the position of each tile. For example, tileposition information indicates the absolute coordinates or relativecoordinates of each tile.

It should be noted that part or all of the above-mentioned informationmay be provided for each tile or each group of tiles (e.g., for eachframe or group of frames).

The three-dimensional data encoding device may include tile additionalinformation in supplemental enhancement information (SEI) and transmitthe SEI. Alternatively, the three-dimensional data encoding device maystore tile additional information in an existing parameter set (PPS,GPS, or APS, etc.) and transmit the parameter set.

For example, when tile additional information changes for each frame,the tile additional information may be stored in a parameter set foreach frame (GPS or APS etc.). When tile additional information does notchange in a sequence, the tile additional information may be stored in aparameter set for sequence (geometry SPS or attribute SPS). Further,when the same tile division information is used for geometry informationand attribute information, tile additional information may be stored ina parameter set for a PCC stream (a stream PS).

Moreover, tile additional information may be stored in any one of theabove-mentioned parameter sets or in parameter sets. In addition, tileadditional information may be stored in the header of encoded data.Additionally, tile additional information may be stored in the header ofa NAL unit.

Furthermore, part or all of tile additional information may be stored inone of the header of divided geometry information and the header ofdivided attribute information, and need not be stored in the other. Forexample, when the same tile additional information is used for geometryinformation and attribute information, the tile additional informationmay be included in the header of one of the geometry information and theattribute information. For example, when attribute information dependson geometry information, the geometry information is processed first.For this reason, the tile additional information may be included in theheader of the geometry information, and need not be included in theheader of the attribute information. In this case, for example, thethree-dimensional data decoding device determines that the attributeinformation of the depender belongs to the same tile as a tile havingthe geometry information of the dependee.

The three-dimensional data decoding device reconstructs point cloud datasubjected to tile division, based on tile additional information. Whenthere are pieces of overlapping point cloud data, the three-dimensionaldata decoding device specifies the pieces of overlapping point clouddata and selects one of the pieces of overlapping point cloud data ormerges pieces of point cloud data.

Moreover, the three-dimensional data decoding device may performdecoding using tile additional information. For example, when tilesoverlap each other, the three-dimensional data decoding device mayperform decoding for each tile, perform processing (e.g., smoothing orfiltering) using the pieces of decoded data, and generate point clouddata. This makes it possible to perform highly accurate decoding.

FIG. 59 is a diagram illustrating a configuration example of a systemincluding the three-dimensional data encoding device and thethree-dimensional data decoding device. Tile divider 5051 divides pointcloud data including geometry information and attribute information intoa first tile and a second tile. In addition, tile divider 5051 transmitstile additional information regarding tile division to decoder 5053 andtile combiner 5054.

Encoder 5052 generates encoded data by encoding the first tile and thesecond tile.

Decoder 5053 restores the first tile and the second tile by decoding theencoded data generated by encoder 5052. Tile combiner 5054 restores thepoint cloud data (the geometry information and the attributeinformation) by combining the first tile and the second tile using thetile additional information.

The following describes slice additional information. Thethree-dimensional data encoding device generates slice additionalinformation that is metadata regarding a slice division method, andtransmits the generated slice additional information to thethree-dimensional data decoding device.

FIG. 60 is a diagram illustrating an example of syntax of sliceadditional information (SliceMetaData). As shown in FIG. 60, forexample, slice additional information includes division methodinformation (type_of_divide), an overlap flag (slice_overlap_flag),overlap information (type_of_overlap), a slice number (slice_number),slice position information (global_position, relative_position), andslice size information (slice_bounding_box_size).

Division method information (type_of_divide) indicates a slice divisionmethod. For example, division method information indicates whether aslice division method is division based on information about an object(object) as shown in FIG. 50. It should be noted that slice additionalinformation may include information indicating an object divisionmethod. For example, this information indicates whether one object is tobe divided into slices or assigned to one slice. In addition, theinformation may indicate, for example, a division number when one objectis divided into slices.

An overlap flag (slice_overlap_flag) indicates whether slices overlapeach other. Overlap information (type_of_overlap) is included in sliceadditional information when, for example, slices overlap each other.Overlap information indicates, for example, how slices overlap eachother. For example, overlap information indicates the size of anoverlapping region.

A slice number (slice number) indicates the number of slices.

Slice position information (global_position, relative_position) andslice size information (slice_bounding_box_size) are information about aregion of a slice. Slice position information is information foridentifying the position of each slice. For example, slice positioninformation indicates the absolute coordinates or relative coordinatesof each slice. Slice size information (slice_bounding_box_size)indicates the size of each slice. For example, slice size informationindicates the size of a bounding box of each slice.

The three-dimensional data encoding device may include slice additionalinformation in SEI and transmit the SEI. Alternatively, thethree-dimensional data encoding device may store slice additionalinformation in an existing parameter set (PPS, GPS, or APS, etc.) andtransmit the parameter set.

For example, when slice additional information changes for each frame,the slice additional information may be stored in a parameter set foreach frame (GPS or APS etc.). When slice additional information does notchange in a sequence, the slice additional information may be stored ina parameter set for sequence (geometry SPS or attribute SPS). Further,when the same slice division information is used for geometryinformation and attribute information, slice additional information maybe stored in a parameter set for a PCC stream (a stream PS).

Moreover, slice additional information may be stored in any one of theabove-mentioned parameter sets or in parameter sets. In addition, sliceadditional information may be stored in the header of encoded data.Additionally, slice additional information may be stored in the headerof a NAL unit.

Furthermore, part or all of slice additional information may be storedin one of the header of divided geometry information and the header ofdivided attribute information, and need not be stored in the other. Forexample, when the same slice additional information is used for geometryinformation and attribute information, the slice additional informationmay be included in the header of one of the geometry information and theattribute information. For example, when attribute information dependson geometry information, the geometry information is processed first.For this reason, the slice additional information may be included in theheader of the geometry information, and need not be included in theheader of the attribute information. In this case, for example, thethree-dimensional data decoding device determines that the attributeinformation of the depender belongs to the same slice as a slice havingthe geometry information of the dependee.

The three-dimensional data decoding device reconstructs point cloud datasubjected to slice division, based on slice additional information. Whenthere are pieces of overlapping point cloud data, the three-dimensionaldata decoding device specifies the pieces of overlapping point clouddata and selects one of the pieces of overlapping point cloud data ormerges pieces of point cloud data.

Moreover, the three-dimensional data decoding device may performdecoding using slice additional information. For example, when slicesoverlap each other, the three-dimensional data decoding device mayperform decoding for each slice, perform processing (e.g., smoothing orfiltering) using the pieces of decoded data, and generate point clouddata. This makes it possible to perform highly accurate decoding.

FIG. 61 is a flowchart of a three-dimensional data encoding processincluding a tile additional information generation process performed bythe three-dimensional data encoding device according to the presentembodiment.

First, the three-dimensional data encoding device determines a divisionmethod to be used (S5031). Specifically, the three-dimensional dataencoding device determines whether a division method based on top view(top_view) or another method (other) is to be used as a tile divisionmethod. In addition, the three-dimensional data encoding devicedetermines a tile shape when the division method based on top view isused. Additionally, the three-dimensional data encoding devicedetermines whether tiles overlap with other tiles.

When the tile division method determined in step S5031 is the divisionmethod based on top view (YES in S5032), the three-dimensional dataencoding device includes a result of the determination that the tiledivision method is the division method based on top view (top_view), intile additional information (S5033).

On the other hand, when the tile division method determined in stepS5031 is a method other than the division method based on top view (NOin S5032), the three-dimensional data encoding device includes a resultof the determination that the tile division method is the method otherthan the division method based on top view (top_view), in tileadditional information (S5034).

Moreover, when a shape in top view of a tile determined in step S5031 isa square (SQUARE in S5035), the three-dimensional data encoding deviceincludes a result of the determination that the shape in top view of thetile is the square, in the tile additional information (S5036). Incontrast, when a shape in top view of a tile determined in step S5031 isa circle (CIRCLE in S5035), the three-dimensional data encoding deviceincludes a result of the determination that the shape in top view of thetile is the circle, in the tile additional information (S5037).

Next, the three-dimensional data encoding device determines whethertiles overlap with other tiles (S5038). When the tiles overlap with theother tiles (YES in S5038), the three-dimensional data encoding deviceincludes a result of the determination that the tiles overlap with theother tiles, in the tile additional information (S5039). On the otherhand, when the tiles do not overlap with other tiles (NO in S5038), thethree-dimensional data encoding device includes a result of thedetermination that the tiles do not overlap with the other tiles, in thetile additional information (S5040).

Finally, the three-dimensional data encoding device divides the tilesbased on the tile division method determined in step S5031, encodes eachof the tiles, and transmits the generated encoded data and the tileadditional information (S5041).

FIG. 62 is a flowchart of a three-dimensional data decoding processperformed by the three-dimensional data decoding device according to thepresent embodiment using tile additional information.

First, the three-dimensional data decoding device analyzes tileadditional information included in a bitstream (S5051).

When the tile additional information indicates that tiles do not overlapwith other tiles (NO in S5052), the three-dimensional data decodingdevice generates point cloud data of each tile by decoding the tile(S5053). Finally, the three-dimensional data decoding devicereconstructs point cloud data from the point cloud data of each tile,based on a tile division method and a tile shape indicated by the tileadditional information (S5054).

In contrast, when the tile additional information indicates that tilesoverlap with other tiles (YES in S5052), the three-dimensional datadecoding device generates point cloud data of each tile by decoding thetile. In addition, the three-dimensional data decoding device identifiesoverlap portions of the tiles based on the tile additional information(S5055). It should be noted that, regarding the overlap portions, thethree-dimensional data decoding device may perform decoding using piecesof overlapping information. Finally, the three-dimensional data decodingdevice reconstructs point cloud data from the point cloud data of eachtile, based on a tile division method, a tile shape, and overlapinformation indicated by the tile additional information (S5056).

The following describes, for example, variations regarding slice. Thethree-dimensional data encoding device may transmit, as additionalinformation, information indicating a type (a road, a building, a tree,etc.) or attribute (dynamic information, static information, etc.) of anobject. Alternatively, a coding parameter may be predetermined accordingto an object, and the three-dimensional data encoding device may notifythe coding parameter to the three-dimensional data decoding device bytransmitting a type or attribute of the object.

The following methods may be used regarding slice data encoding orderand transmitting order. For example, the three-dimensional data encodingdevice may encode slice data in decreasing order of ease of objectrecognition or clustering. Alternatively, the three-dimensional dataencoding device may encode slice data in the order in which clusteringis completed. Moreover, the three-dimensional data encoding device maytransmit slice data in the order in which the slice data is encoded.Alternatively, the three-dimensional data encoding device may transmitslice data in decreasing order of priority for decoding in anapplication. For example, when dynamic information has high priority fordecoding, the three-dimensional data encoding device may transmit slicedata in the order in which slices are grouped using the dynamicinformation.

Furthermore, when encoded data order is different from the order ofpriority for decoding, the three-dimensional data encoding device maytransmit encoded data after rearranging the encoded data. In addition,when storing encoded data, the three-dimensional data encoding devicemay store encoded data after rearranging the encoded data.

An application (the three-dimensional data decoding device) requests aserver (the three-dimensional data encoding device) to transmit slicesincluding desired data. The server may transmit slice data required bythe application, and need not transmit slice data unnecessary for theapplication.

An application requests a server to transmit a tile including desireddata. The server may transmit tile data required by the application, andneed not transmit tile data unnecessary for the application.

As stated above, the three-dimensional data encoding device according tothe present embodiment performs the process shown in FIG. 63. First, thethree-dimensional data encoding device encodes subspaces (e.g., tiles)obtained by dividing a current space which includes three-dimensionalpoints, to generate pieces of encoded data (S5061). Thethree-dimensional data encoding device generates a bitstream includingthe pieces of encoded data and first information (e.g., topview_shape)indicating a shape of each of the subspaces (S5062).

Accordingly, since the three-dimensional data encoding device can selectany shape from various types of shapes of subspaces, thethree-dimensional data encoding device can improve the codingefficiency.

For example, the shape is a two-dimensional shape or a three-dimensionalshape of each of the subspaces. For example, the shape is a shape in atop view of the subspace. To put it another way, the first informationindicates a shape of the subspace viewed from a specific direction(e.g., an upper direction). In short, the first information indicates ashape in an overhead view of the subspace. For example, the shape isrectangular or circular.

For example, the bitstream includes second information (e.g.,tile_overlap_flag) indicating whether the subspaces overlap.

Accordingly, since the three-dimensional data encoding device allowssubspaces to overlap, the three-dimensional data encoding device cangenerate the subspaces without making a shape of each of the subspacescomplex.

For example, the bitstream includes third information (e.g.,type_of_divide) indicating whether a division method used to obtain thesubspaces is a division method using a top view.

For example, the bitstream includes fourth information (e.g.,tile_height) indicating at least one of a height, a width, a depth, or aradius of each of the subspaces.

For example, the bitstream includes fifth information (e.g.,global_position or relative_position) indicating a position of each ofthe subspaces.

For example, the bitstream includes sixth information (e.g.,tile_number) indicating a total number of the subspaces.

For example, the bitstream includes seventh information indicating aninterval between the subspaces.

For example, the three-dimensional data encoding device includes aprocessor and memory, and the processor performs the above process usingthe memory.

Moreover, the three-dimensional data decoding device according to thepresent embodiment performs the process shown in FIG. 64. First, thethree-dimensional data decoding device decodes pieces of encoded dataincluded in a bitstream and generated by encoding subspaces (e.g.,tiles) obtained by dividing a current space which includesthree-dimensional points, to restore the subspaces (S5071). Thethree-dimensional data decoding device restores the current space bycombining the subspaces using first information (e.g., topview_shape)which is included in the bitstream and indicates a shape of each of thesubspaces (S5072). For example, the three-dimensional data decodingdevice can determine a position and a range of each of subspaces in acurrent space by recognizing a shape of the subspace using the firstinformation. The three-dimensional data decoding device can combine thesubspaces based on the determined positions and ranges of the subspaces.Accordingly, the three-dimensional data decoding device can combine thesubspaces correctly.

For example, the shape is a two-dimensional shape or a three-dimensionalshape of each of the subspaces. For example, the shape is rectangular orcircular.

For example, the bitstream includes second information (e.g.,tile_overlap_flag) indicating whether the subspaces overlap. In therestoring of the current space, the three-dimensional data decodingdevice combines the subspaces by further using the second information.For example, the three-dimensional data decoding device determineswhether subspaces overlap, using the second information. When thesubspaces overlap, the three-dimensional data decoding device identifiesoverlap regions and performs a predetermined process on the identifiedregions.

For example, the bitstream includes third information (e.g.,type_of_divide) indicating whether a division method used to obtain thesubspaces is a division method using a top view. In the restoring of thecurrent space, when the third information indicates that the divisionmethod used to obtain the subspaces is the division method using the topview, the three-dimensional data decoding device combines the subspacesusing the first information.

For example, the bitstream includes fourth information (e.g.,tile_height) indicating at least one of a height, a width, a depth, or aradius of each of the subspaces. In the restoring of the current space,the three-dimensional data decoding device combines the subspaces byfurther using the fourth information. For example, the three-dimensionaldata decoding device can determine a position and a range of each ofsubspaces in a current space by recognizing a height of the subspaceusing the fourth information. The three-dimensional data decoding devicecan combine the subspaces based on the determined positions and rangesof the subspaces.

For example, the bitstream includes fifth information (e.g.,global_position or relative_position) indicating a position of each ofthe subspaces. In the restoring of the current space, thethree-dimensional data decoding device combines the subspaces by furtherusing the fifth information. For example, the three-dimensional datadecoding device can determine a position of each of subspaces in acurrent space by recognizing a position of the subspace using the fifthinformation. The three-dimensional data decoding device can combine thesubspaces based on the determined positions of the subspaces.

For example, the bitstream includes sixth information (e.g.,tile_number) indicating a total number of the subspaces. In therestoring of the current space, the three-dimensional data decodingdevice combines the subspaces by further using the sixth information.

For example, the bitstream includes seventh information indicating aninterval between the subspaces. In the restoring of the current space,the three-dimensional data decoding device combines the subspaces byfurther using the seventh information. For example, thethree-dimensional data decoding device can determine a position and arange of each of subspaces in a current space by recognizing an intervalbetween the subspaces using the seventh information. Thethree-dimensional data decoding device can combine the subspaces basedon the determined positions and ranges of the subspaces.

For example, the three-dimensional data decoding device includes aprocessor and memory, and the processor performs the above process usingthe memory.

Embodiment 7

The present embodiment describes processing of a division unit (e.g., atile or a slice) including no points. First, a method of dividing pointcloud data will be described.

In a video coding standard such as HEVC, since there are data for allthe pixels of a two-dimensional image, even when a two-dimensional spaceis divided into data areas, all the data areas include data. On theother hand, in encoding of three-dimensional point cloud data, pointsthemselves that are elements of point cloud data are data, and there isa possibility that data are not included in some of areas.

There are various methods of spatially dividing point cloud data, andsuch methods can be classified according to whether a division unit(e.g., a tile or a slice) that is a divided data unit always includesone or more point data.

A division method in which all division units each include one or morepoint data is referred to as a first division method. Examples of thefirst division method include a method of dividing point cloud data inconsideration of processing time for encoding or the size of encodeddata. In this case, each division unit has a substantially even numberof points.

FIG. 65 is a diagram illustrating examples of a division method. Forexample, as shown in (a) in FIG. 65, a method of separating pointsbelonging to an identical space into two identical spaces may be used asthe first division method. In addition, as shown in (b) in FIG. 65, aspace may be divided into subspaces (division units) so that each of thedivision units includes points.

Since these methods are division in consideration of points, alldivision units always include one or more points.

A division method in which division units are likely to include one ormore division units including no point data is referred to as a seconddivision method. For example, as shown in (c) in FIG. 65, a method ofdividing a space equally may be used as the second division method. Inthis case, a division unit does not always include points. In short, adivision unit may include no points.

When the three-dimensional data encoding device divides point clouddata, the three-dimensional data encoding device may include, in dividedadditional information (e.g., tile additional information or sliceadditional information), (i) whether a division method in which alldivision units include one or more point data has been used, (ii)whether a division method in which division units include one or moredivision units including no point data has been used, or (iii) whether adivision method in which division units are likely to include one ormore division units including no point data. Subsequently, thethree-dimensional data encoding device may transmit the dividedadditional information.

It should be noted that the three-dimensional data encoding device mayindicate the above information as a type of a division method.Additionally, the three-dimensional data encoding device may performdivision using a predetermined division method, and need not transmitdivided additional information. In this case, the three-dimensional dataencoding device clearly specifies whether the division method is thefirst division method or the second division method in advance.

The following describes the second division method and an example ofgenerating and transmitting encoded data. It should be noted thatalthough tile division will be exemplified as a method of dividing athree-dimensional space below, the present embodiment is not limited totile division, and the following procedure is applicable to a divisionmethod using division units other than tiles. For example, slicedivision may be used instead of tile division.

FIG. 66 is a diagram illustrating an example of dividing point clouddata into six tiles. FIG. 66 shows an example in which the smallest unitis a point and geometry information (geometry) and attribute information(attribute) are divided together. It should be noted that the sameapplies to a case in which geometry information and attributeinformation are divided using separate division methods or by separatedivision numbers, a case in which there is no attribute information, anda case in which there are pieces of attribute information.

In the example shown in FIG. 66, tile division results in tiles (#1, #2,#4, #6) including points and tiles (#3, #5) including no points. A tileincluding no points is referred to as a null tile.

It should be noted that the present disclosure is not limited to thedivision into six tiles, and any division method may be used. Forexample, a division unit may be a cube or have a non-cubic shape such asa cuboid or round column. Division units may be identical or differentin shape. Moreover, a predetermined method may be used as a divisionmethod, or a different method may be used for each predetermined unit(e.g., PCC frame).

In the present division method, when point cloud data is divided intotiles and one or more of the tiles include no data, a bitstreamincluding information indicating that the one or more tiles are nulltiles is generated.

The following describes a method of transmitting a null tile and amethod of signaling a null tile. The three-dimensional data encodingdevice may generate, as addition information (metadata) regarding datadivision, for example, the following information and transmit thegenerated information. FIG. 67 is a diagram illustrating an example ofsyntax of tile additional information (TileMetaData). Tile additionalinformation includes division method information (type_of_divide),division method null information (type_of_divide_null), a tile divisionnumber (number_of_tiles), and a tile null flag (tile_null_flag).

Division method information (type_of_divide) is information regarding adivision method or a division type. For example, division methodinformation indicates one or more division methods or division types.Examples of a division method include top view (top_view) division andequal division. It should be noted that when the number of definitionsof a division method is one, tile additional information need notinclude division method information.

Division method null information (type_of_divide null) is informationindicating whether a division method to be used is the following firstdivision method or second division method. Here, the first divisionmethod is a division method in which each of all division units alwaysincludes one or more point data. The second division method is adivision method in which division units include one or more divisionunits including no point data or a division method in which divisionunits are likely to include one or more division units including nopoint data.

Tile additional information may also include, as division informationabout tiles as a whole, at least one of (i) information (a tile divisionnumber (number_of_tiles)) indicating a tile division number orinformation for specifying a tile division number, (ii) informationindicating the number of null tiles or information for specifying thenumber of null tiles, or (iii) information indicating thenumber_of_tiles other than null tiles or information for specifying thenumber of tiles other than null tiles. In addition, the tile additionalinformation may include, as division information about tiles as a whole,information indicating shapes of tiles or whether tiles overlap eachother.

Moreover, the tile additional information indicates division informationof each tile in sequence. For example, the order of tiles ispredetermined for each division method, and is already known to thethree-dimensional data encoding device and the three-dimensional datadecoding device. It should be noted that when the order of tiles is notpredetermined, the three-dimensional data encoding device may transmitinformation indicating the order to the three-dimensional data decodingdevice.

Division information of each tile includes a tile null flag(tile_null_flag) indicating whether the tile includes data (a point). Itshould be noted that when a tile includes no data, a tile null flag maybe included as tile division information.

Moreover, when a tile is not a null tile, tile additional informationincludes division information (position information (e.g., thecoordinates of the origin (origin_x, origin_y, origin_z), tile heightinformation, etc.) of each tile. Furthermore, when a tile is a nulltile, tile additional information does not include division informationof each tile.

For example, when slice division information of each tile is stored intodivision information of each tile, the three-dimensional data encodingdevice need not store slice division information of a null tile intoadditional information.

It should be noted that in this example, a tile division number(number_of_tiles) indicates the number of tiles including null tiles.FIG. 68 is a diagram illustrating an example of index information (idx)of a tile. In the example shown in FIG. 68, index information is alsoassigned to a null tile.

The following describes a data structure of encoded data including nulltiles and a transmission method. FIG. 69 to FIG. 71 each are a diagramillustrating a data structure when the third and fifth tiles include nodata after geometry information and attribute information are dividedinto six tiles.

FIG. 69 is a diagram illustrating an example of a dependencyrelationship of each data. The pointed end of an arrow in the figureindicates a dependee, and the other end of the arrow indicates adepender. Moreover, in the figure, G_(tn) denotes geometry informationfor tile number n, and A_(tn) denotes attribute information for tilenumber n, n being an integer from 1 to 6. M_(tile) denotes tileadditional information.

FIG. 70 is a diagram illustrating a structural example of transmitteddata that is encoded data transmitted by the three-dimensional dataencoding device. FIG. 71 is a diagram illustrating a structure ofencoded data and a method of storing encoded data in a NAL unit.

As shown in FIG. 71, each of the headers of data of geometry information(divided geometry information) and attribute information (dividedattribute information) includes index information (tile_idx) of a tile.

Moreover, as shown in structure 1 in FIG. 70, the three-dimensional dataencoding device need not transmit geometry information or attributeinformation constituting a null tile. Alternatively, as shown instructure 2 in FIG. 70, the three-dimensional data encoding device maytransmit, as data of a null tile, information indicating that a tile isa null tile. For example, the three-dimensional data encoding device mayinclude, in tile_type stored in the header of a NAL unit or the headerin a payload (nal_unit_payload) of a NAL unit, that a type of the datais a null tile, and transmit the header. It should be noted that thefollowing description will be premised on structure 1.

In structure 1, when there are null tiles, some of values of indexinformation (tile_idx) of tiles included in the header of geometryinformation data or attribute information data are missing and thevalues are not continuous in transmitted data.

Moreover, when data have a dependency relationship with each other, thethree-dimensional data encoding device transmits the data so that datareferred to can be decoded before data referring to the data. It shouldbe noted that a tile of attribute information depends on a tile ofgeometry information. The same index number of a tile is assigned toattribute information and geometry information having a dependencyrelationship with each other.

It should be noted that tile additional information regarding tiledivision may be stored in both or one of a parameter set for geometryinformation (GPS) and a parameter set for attribute information (APS).When the tile additional information is stored in one of the GPS or theAPS, reference information indicating a GPS or an APS to be referred tomay be stored in the other of the GPS or the APS. Moreover, when a tiledivision method is different between geometry information and attributeinformation, different tile additional information is stored in each ofa GPS and an APS. Furthermore, when an identical tile division method isused for sequences (PCC frames), tile additional information may bestored in a GPS, an APS, or a sequence parameter set (SPS).

For example, when tile additional information is stored in both a GPSand an APS, tile additional information for geometry information isstored in the GPS, and tile additional information for attributeinformation is stored in the APS. Moreover, when tile additionalinformation is stored in common information such as an SPS, tileadditional information to be commonly used for geometry information andattribute information may be stored, or tile additional information forthe geometry information and tile additional information for theattribute information may be stored separately.

Hereinafter, a combination of tile division and slice division will bedescribed. First, the following describe a data structure and datatransmission when tile division is performed after slice division.

FIG. 72 is a diagram illustrating an example of a dependencyrelationship of each data when tile division is performed after slicedivision. The pointed end of an arrow in the figure indicates adependee, and the other end of the arrow indicates a depender. Dataindicated by a solid line in the figure is data actually transmitted,and data indicated by a broken line is data not transmitted.

In the figure, G denotes geometry information, and A denotes attributeinformation. G_(s1) denotes geometry information for slice number 1, andG_(s2) denotes geometry information for slice number 2. G_(s1t1) denotesgeometry information for slice number 1 and tile number 1, and G_(s2t2)denotes geometry information for slice number 2 and tile number 2.Likewise, A_(s1) denotes attribute information for slice number 1, andA_(s2) denotes attribute information for slice number 2. A_(s1t1)denotes attribute information for slice number 1 and tile number 1, andA_(s2t1) denotes attribute information for slice number 2 and tilenumber 1.

M_(slice) denotes slice additional information, MG_(tile) denotesgeometry tile additional information, and MA_(tile) denotes attributetile additional information. D_(s1t1) denotes dependency relationshipinformation of attribute information A_(s1t1), and D_(s2t1) denotesdependency relationship information of attribute information A_(s2t1).

The three-dimensional data encoding device need not generate andtransmit geometry information and attribute information regarding a nulltile.

Even when a tile division number is identical to all slices, there is apossibility that the number of tiles generated and transmitted isdifferent between slices. For example, when a tile division number isdifferent between geometry information and attribute information, thereis a case in which a null tile is included in one of the geometryinformation and the attribute information, and a null tile is notincluded in the other of the geometry information and the attributeinformation. In the example shown in FIG. 72, geometry information ofslice 1 (G_(s1)) is divided into two tiles G_(s1t1) and G_(s1t2), andG_(s1t2) is a null tile. In contrast, attribute information of slice 1(A_(s1)) is not divided, with the result that there are one A_(s1t1) andno null tiles.

When data is included in at least a tile of attribution informationregardless of whether a null tile is included in a slice of geometryinformation, the three-dimensional data encoding device generates andtransmits dependency relationship information of the attributeinformation. For example, when the three-dimensional data encodingdevice stores slice division information of each tile in divisioninformation of each slice included in slice additional informationregarding slice division, the three-dimensional data encoding devicestores information indicating whether the tile is a null tile in theslice division information.

FIG. 73 is a diagram illustrating an example of decoding order of data.In the example shown in FIG. 73, data are decoded in order from theleft. The three-dimensional data decoding device decodes, out of datahaving a dependency relationship with each other, data of a dependeefirst. For example, the three-dimensional data encoding devicerearranges data in this order and transmits the data. It should be notedthat any order may be used as long as data of a dependee takesprecedence. Moreover, the three-dimensional data encoding device maytransmit additional information and dependency relationship informationbefore data.

Next, the following describe a data structure and data transmission whenslice division is performed after tile division.

FIG. 74 is a diagram illustrating an example of a dependencyrelationship of each data when slice division is performed after tiledivision. The pointed end of an arrow in the figure indicates adependee, and the other end of the arrow indicates a depender. Dataindicated by a solid line in the figure is data actually transmitted,and data indicated by a broken line is data not transmitted.

In the figure, G denotes geometry information, and A denotes attributeinformation. G_(t1) denotes geometry information for tile number 1. Gustdenotes geometry information for tile number 1 and slice number 1, andG_(t1s2) denotes geometry information for tile number 1 and slice number2. Likewise, A_(t1) denotes attribute information for tile number 1, andA_(t1s1) denotes attribute information for tile number 1 and slicenumber 1.

M_(tile) denotes tile additional information, MG_(slice) denotesgeometry slice additional information, and MA_(slice) denotes attributeslice additional information. D_(t1s1) denotes dependency relationshipinformation of attribute information A_(t1s1), and D_(t2s1) denotesdependency relationship information of attribute information A_(t2s1).

The three-dimensional data encoding device does not perform slicedivision on a null tile. In addition, the three-dimensional dataencoding device need not generate and transmit geometry information andattribute information regarding a null tile, and dependency relationshipinformation of the geometry information.

FIG. 75 is a diagram illustrating an example of decoding order of data.In the example shown in FIG. 75, data are decoded in order from theleft. The three-dimensional data decoding device decodes, out of datahaving a dependency relationship with each other, data of a dependeefirst. For example, the three-dimensional data encoding devicerearranges data in this order and transmits the data. It should be notedthat any order may be used as long as data of a dependee takesprecedence. Moreover, the three-dimensional data encoding device maytransmit additional information and dependency relationship informationbefore data.

The following describes procedures of a point cloud data divisionprocess and a point cloud data combination process. It should be notedthat although examples of tile division and slice division will bedescribed here, the same procedures can be applied to division ofanother space.

FIG. 76 is a flowchart of a three-dimensional data encoding processincluding a data division process performed by the three-dimensionaldata encoding device. First, the three-dimensional data encoding devicedetermines a division method to be used (S5101). Specifically, thethree-dimensional data encoding device determines whether to use a firstdivision method or a second division method. For example, thethree-dimensional data encoding device may determine a division methodbased on instructions from a user or an external device (e.g., thethree-dimensional data decoding device), or determine a division methodaccording to inputted point cloud data. In addition, a division methodto be used may be predetermined.

Here, the first division method is a division method in which each ofall division units (tiles or slices) always includes one or more pointdata. The second division method is a division method in which divisionunits include one or more division units including no point data or adivision method in which division units are likely to include one ormore division units including no point data.

When the determined division method is the first division method (FIRSTDIVISION METHOD in S5102), the three-dimensional data encoding deviceincludes a result of the determination that the division method used isthe first division method, in divided additional information (e.g., tileadditional information or slice additional information) that is metadataregarding data division (S5103). Finally, the three-dimensional dataencoding device encodes all division units (S5104).

On the other hand, when the determined division method is the seconddivision method (SECOND DIVISION METHOD in S5102), the three-dimensionaldata encoding device includes a result of the determination that thedivision method used in the second division method, in dividedadditional information (S5105). Finally, the three-dimensional dataencoding device encodes, among division units, division units other thandivision units (e.g., null tiles) including no point data (S5106).

FIG. 77 is a flowchart of a three-dimensional data decoding processincluding a data combination process performed by the three-dimensionaldata decoding device. First, the three-dimensional data decoding devicerefers to divided additional information included in a bitstream anddetermines whether a division method used is the first division methodor the second division method (S5111).

When the division method used is the first division method (FIRSTDIVISION METHOD in S5112), the three-dimensional data decoding devicereceives encoded data of all division units and generates decoded dataof all the division units by decoding the received encoded data (S5113).Finally, the three-dimensional data decoding device reconstructs athree-dimensional point cloud using the decoded data of all the divisionunits (S5114). For example, the three-dimensional data decoding devicereconstructs a three-dimensional point cloud by combining divisionunits.

On the other hand, when the division method used is the second divisionmethod (SECOND DIVISION METHOD in S5112), the three-dimensional datadecoding device receives encoded data of division units including pointdata and encoded data of division units including no point data, andgenerates decoded data by decoding the received encoded data of thedivision units (S5115). It should be noted that when division unitsincluding no point data are not transmitted, the three-dimensional datadecoding device need not receive and decode the division units includingno point data. Finally, the three-dimensional data decoding devicereconstructs a three-dimensional point cloud using the decoded data ofthe division units including the point data (S5116). For example, thethree-dimensional data decoding device reconstructs a three-dimensionalpoint cloud by combining division units.

The following describes other point cloud data division methods. When aspace is divided equally as shown in (c) in FIG. 65, a divided space mayinclude no points. In this case, the three-dimensional data encodingdevice combines the space including no points with another spaceincluding points. As a result, the three-dimensional data encodingdevice can form division units so that each of the division unitsincludes one or more points.

FIG. 78 is a flowchart for data division in the above case. First, thethree-dimensional data encoding device divides data using a specificmethod (S5121). For example, the specific method is the above seconddivision method.

Next, the three-dimensional data encoding device determines whether acurrent division unit that is a division unit to be processed includespoints (S5122). When the current division unit includes points (YES inS5122), the three-dimensional data encoding device encodes the currentdivision unit (S5123). On the other hand, when the current division unitincludes no points (NO in S5122), the three-dimensional data encodingdevice combines the current division unit with another division unitincluding points, and encodes the combined division unit (S5124). To putit another way, the three-dimensional data encoding device encodes thecurrent division unit together with the other division unit includingthe points.

It should be noted that although the example of performing determinationand combination for each division unit has been described above, aprocessing method is not limited to this. For example, thethree-dimensional data encoding device may determine whether each ofdivision units includes points, perform combination so that any divisionunit including no points will disappear, and encode each of the combineddivision units.

The following describes a method of transmitting data including a nulltile. When a current tile that is a tile to be processed is a null tile,the three-dimensional data encoding device does not transmit data of thecurrent tile. FIG. 79 is a flowchart of a data transmission process.

First, the three-dimensional data encoding device determines a tiledivision method and divides point cloud data into tiles using thedetermined division method (S5131).

Next, the three-dimensional data encoding device determines whether thecurrent tile is a null tile (S5132). In other words, thethree-dimensional data encoding device determines whether no data isincluded in the current tile.

When the current tile is the null tile (YES in S5132), thethree-dimensional data encoding device includes a result of thedetermination that the current tile is the null tile, in tile additionalinformation, and does not include information (tile position, size,etc.) about the current tile in the tile additional information (S5133).In addition, the three-dimensional data encoding device does nottransmit the current tile (S5134).

On the other hand, when the current tile is not the null tile (NO inS5132), the three-dimensional data encoding device includes a result ofthe determination that the current tile is not the null tile, in tileadditional information, and includes information about each tile in thetile additional information (S5135). In addition, the three-dimensionaldata encoding device transmits the current tile (S5136).

As stated above, it is possible to reduce the amount of tile additionalinformation by omitting information about a null tile from the tileadditional information.

The following describes a method of decoding encoded data including anull tile. First, a process when there is no packet loss will bedescribed.

FIG. 80 is a diagram illustrating an example of transmitted data that isencoded data transmitted by the three-dimensional data encoding device,and an example of received data inputted to the three-dimensional datadecoding device. It should be noted that a system environment withoutpacket loss is assumed here, and received data is identical totransmitted data.

When a system environment is free from packet loss, thethree-dimensional data decoding device receives all transmitted data.FIG. 81 is a flowchart of a process performed by the three-dimensionaldata decoding device.

First, the three-dimensional data decoding device refers to tileadditional information (S5141) and determines whether each of tiles is anull tile (S5142).

When the tile additional information indicates that a current tile isnot a null tile (NO in S5142), the three-dimensional data decodingdevice determines that the current tile is not the null tile and decodesthe current tile (S5143). Finally, the three-dimensional data decodingdevice obtains information (position information (e.g., origincoordinates), size, etc. of the tiles) about the tiles from the tileadditional information, and reconstructs three-dimensional data bycombining the tiles using the obtained information (S5144).

On the other hand, when the tile additional information indicates that acurrent tile is a null tile (YES in S5142), the three-dimensional datadecoding device determines that the current tile is the null tile anddoes not decode the current tile (S5145).

It should be noted that the three-dimensional data decoding device maydetermine that missing data is a null tile, by sequentially analyzingindex information indicated by the header of encoded data. In addition,the three-dimensional data decoding device may combine a determinationmethod using tile additional information and a determination methodusing index information.

The following describes a process when there is packet loss. FIG. 82 isa diagram illustrating an example of transmitted data from thethree-dimensional data encoding device, and an example of received datainputted to the three-dimensional data decoding device. Here, a systemenvironment with packet loss is assumed.

When packet loss occurs in a system environment, there is a possibilitythat the three-dimensional data decoding device cannot receive alltransmitted data. In this example, packets of G_(t2) and A_(t2) arelost.

FIG. 83 is a flowchart of a process performed by the three-dimensionaldata decoding device in the above case. First, the three-dimensionaldata decoding device analyzes the continuity of index informationindicated by the header of encoded data (S5151) and determines whetheran index number of a current tile is present (S5152).

When the index number of the current tile is present (YES in S5152), thethree-dimensional data decoding device determines that the current tileis not a null tile and decodes the current tile (S5153). Finally, thethree-dimensional data decoding device obtains information (positioninformation (e.g., origin coordinates), size, etc. of tiles) about tilesfrom tile additional information, and reconstructs three-dimensionaldata by combining the tiles using the obtained information (S5154).

On the other hand, when the index number of the current tile is notpresent (NO in S5152), the three-dimensional data decoding device refersto tile additional information (S5155) and determines whether thecurrent tile is a null tile (S5156).

When the current tile is not the null tile (NO in S5156), thethree-dimensional data decoding device determines that the current tileis lost (packet loss) and performs error decoding (S5157). Errordecoding is, for example, a process of trying to decode original dataassuming that the data existed. In this case, the three-dimensional datadecoding device may regenerate three-dimensional data and reconstructthree-dimensional data (S5154).

In contrast, when the current tile is the null tile (YES in S5156), thethree-dimensional data decoding device determines that the current tileis the null tile, and performs neither decoding nor the reconstructionof three-dimensional data (S5158).

The following describes an encoding method when no null tiles areclearly shown. The three-dimensional data encoding device may generateencoded data and additional information using the following method.

The three-dimensional data encoding device does not include informationabout a null tile in tile additional information. The three-dimensionaldata encoding device appends index numbers of tiles other than the nulltile to a data header. The three-dimensional data encoding device doesnot transmit the null tile.

In this case, a tile division number (number_of_tiles) indicates adivision number excluding a null tile. It should be noted that thethree-dimensional data encoding device may separately store informationindicating the number of null tiles in a bitstream. In addition, thethree-dimensional data encoding device may include information about anull tile in additional information or include part of information abouta null tile in the additional information.

FIG. 84 is a flowchart of a three-dimensional data encoding processperformed by the three-dimensional data decoding device in the abovecase. First, the three-dimensional data encoding device determines atile division method and divides point cloud data into tiles using thedetermined division method (S5161).

Next, the three-dimensional data encoding device determines whether acurrent tile is a null tile (S5162). In other words, thethree-dimensional data encoding device determines whether no data isincluded in the current tile.

When the current tile is not the null tile (NO in S5162), thethree-dimensional data encoding device appends index information of thecurrent tile other than a null tile to a data header (S5163). Finally,the three-dimensional data encoding device transmits the current tile(S5164).

On the other hand, when the current tile is the null tile (YES inS5162), the three-dimensional data encoding device neither appends indexinformation of the current tile to a data header nor transmits thecurrent tile.

FIG. 85 is a diagram illustrating an example of index information (idx)to be appended to a data header. As shown in FIG. 85, index informationof any null tile is not appended, and serial numbers are put on tilesother than null tiles.

FIG. 86 is a diagram illustrating an example of a dependencyrelationship of each data. The pointed end of an arrow in the figureindicates a dependee, and the other end of the arrow indicates adepender. Moreover, in the figure, G_(tn) denotes geometry informationfor tile number n, and A_(tn) denotes attribute information for tilenumber n, n being an integer from 1 to 4. M_(tile) denotes tileadditional information.

FIG. 87 is a diagram illustrating a structural example of transmitteddata that is encoded data transmitted by the three-dimensional dataencoding device.

The following describes a decoding method when no null tiles are clearlyshown. FIG. 88 is a diagram illustrating an example of transmitted datafrom the three-dimensional data encoding device, and an example ofreceived data inputted to the three-dimensional data decoding device.Here, a system environment with packet loss is assumed.

FIG. 89 is a flowchart of a process performed by the three-dimensionaldata decoding device in the above case. First, the three-dimensionaldata decoding device analyzes index information of tiles indicated bythe header of encoded data, and determines whether an index number of acurrent tile is present. In addition, the three-dimensional datadecoding device obtains a tile division number from tile additionalinformation (S5171).

When the index number of the current tile is present (YES in S5172), thethree-dimensional data decoding device decodes the current tile (S5173).Finally, the three-dimensional data decoding device obtains information(position information (e.g., origin coordinates), size, etc. of thetiles) about the tiles from the tile additional information, andreconstructs three-dimensional data by combining the tiles using theobtained information (S5175).

In contrast, when the index number of the current tile is not present(NO in S5172), the three-dimensional data decoding device determinesthat the current tile is lost and performs error decoding (S5174). Inaddition, the three-dimensional data decoding device determines that anyspace including no data is a null tile, and reconstructsthree-dimensional data.

By clearly showing null tiles, the three-dimensional data encodingdevice can appropriately determine the absence of points in tiles, notdata unavailability due to, for example, mismeasurement or dataprocessing, or packet loss.

It should be noted that the three-dimensional data encoding device mayuse both a method of clearly showing null packets and a method ofclearly showing no null packets. In this case, the three-dimensionaldata encoding device may include information indicating whether nullpackets are clearly shown, in tile additional information. Moreover,whether null packets are to be clearly shown may be determined inadvance according to a type of a division method, and thethree-dimensional data encoding device may indicate whether the nullpackets are to be clearly shown, by showing the type of the divisionmethod.

Although an example in which information regarding all tiles is includedin tile additional information has been described in FIG. 67 etc.,information regarding some of tiles or information regarding null tilesof some of tiles may be included in tile additional information.

Moreover, although an example in which information regarding divideddata such as information indicating whether divided data (tiles) arepresent is stored in tile additional information has been described,part or all of these pieces of information may be stored in a parameterset or may be stored as data. When these pieces of information arestored as data, for example, nal_unit_type denoting informationindicating whether divided data are present may be defined, and thepieces of information may be stored in a NAL unit. Additionally, thepieces of information may be stored in both additional information anddata.

As stated above, the three-dimensional data encoding device according tothe present embodiment performs the process shown in FIG. 90. First, thethree-dimensional data encoding device generates pieces of encoded databy encoding subspaces (e.g., tiles or slices) obtained by dividing acurrent space including three-dimensional points (S5181). Thethree-dimensional data encoding device generates a bitstream includingthe pieces of encoded data and pieces of first information (e.g.,tile_null_flag) each of which corresponds to a corresponding one of thesubspaces (S5182). Each of the pieces of first information indicateswhether the bitstream includes second information indicating a structureof the corresponding one of the subspaces.

Accordingly, for example, since the second information can be omittedfor a subspace including no points, it is possible to reduce the datavolume of a bitstream.

For example, the second information includes information indicatingorigin coordinates of the corresponding one of the subspaces. Forexample, the second information includes information indicating at leastone of a height, a width, or a depth of the corresponding one of thesubspaces.

Accordingly, the three-dimensional data encoding device can reduce thedata volume of a bitstream.

Moreover, as shown in FIG. 78, the three-dimensional data encodingdevice may divide a current space including three-dimensional pointsinto subspaces (e.g., tiles or slices), combine the subspaces accordingto the number of three-dimensional points included in each of thesubspaces, and encode the combined subspaces. For example, thethree-dimensional data encoding device may combine subspaces so that thenumber of three-dimensional points included in each of the combinedsubspaces is greater than or equal to a predetermined number. Forexample, the three-dimensional data encoding device may combinesubspaces including no three-dimensional points with subspaces includingthree-dimensional points.

Accordingly, since the three-dimensional data encoding device cansuppress the generation of subspaces including fewer points or nopoints, the three-dimensional data encoding device can improve thecoding efficiency.

For example, the three-dimensional data encoding device includes aprocessor and memory, and the memory performs the above process usingthe memory.

The three-dimensional data decoding device according to the presentembodiment performs the process shown in FIG. 91. First, thethree-dimensional data decoding device obtains from a bitstream piecesof first information (e.g., tile_null_flag) each of which (i)corresponds to a corresponding one of subspaces (e.g., tiles or slices)obtained by dividing a current space including three-dimensional pointsand (ii) indicates whether the bitstream includes second informationindicating a structure of the corresponding one of the subspaces(S5191). The three-dimensional data decoding device restores thesubspaces by decoding pieces of encoded data included in the bitstreamand generated by encoding the subspaces, and restores the current spaceby combining the subspaces, using the pieces of first information(S5192). For example, the three-dimensional data decoding devicedetermines whether a bitstream includes second information, using firstinformation; and combines decoded subspaces using the second informationwhen the bitstream includes the second information.

Accordingly, for example, since the second information can be omittedfor a subspace including no points, it is possible to reduce the datavolume of a bitstream.

For example, the second information includes information indicatingorigin coordinates of the corresponding one of the subspaces. Forexample, the second information includes information indicating at leastone of a height, a width, or a depth of the corresponding one of thesubspaces.

Accordingly, the three-dimensional data decoding device can reduce thedata volume of a bitstream.

Moreover, the three-dimensional data decoding device may divide acurrent space including three-dimensional points into subspaces (e.g.,tiles or slices), combine the subspaces according to the number ofthree-dimensional points included in each of the subspaces, receiveencoded data generated by encoding the combined subspaces, and decodethe received encoded data. For example, encoded data may be generated bycombining subspaces so that the number of three-dimensional pointsincluded in each of the combined subspaces is greater than or equal to apredetermined number. For example, three-dimensional data may begenerated by combining subspaces including no three-dimensional pointswith subspaces including three-dimensional points.

Accordingly, the three-dimensional data decoding device can decodeencoded data for which the coding efficiency is improved, by suppressingthe generation of subspaces including fewer points or no points.

For example, the three-dimensional data decoding device includes aprocessor and memory, and the memory performs the above process usingthe memory.

Embodiment 8

FIG. 92 is a block diagram illustrating an exemplary configuration of athree-dimensional data encoding device according to this embodiment.FIG. 93 is a diagram for describing an overview of an encoding methodperformed by the three-dimensional data encoding device according tothis embodiment.

Three-dimensional data encoding device 6800 divides point cloud datainto pieces of divided data such as tiles or slices, and encodes eachpiece of divided data. The divided data is also referred to as sub pointcloud data. The point cloud data indicates three-dimensional positionsin a three-dimensional space. The pieces of divided data are pieces ofsub point cloud data created from the point cloud data by dividing thethree-dimensional space containing the point cloud data into subspaces.The number of subspaces, i.e., the number of pieces of divided data maybe one, which means no division, or two or more.

FIG. 92 will be described for an example in which three-dimensional dataencoding device 6800 divides the point cloud data into two pieces. FIG.93 shows an example in which the point cloud data is divided into fourpieces. Although the description of FIG. 93 assumes that atwo-dimensional space is divided for example, a one-dimensional orthree-dimensional space may be divided.

Three-dimensional data encoding device 6800 includes dividing methoddeterminer 6801, divider 6802, quantizers 6803 a and 6803 b, shiftamount calculators 6804 a and 6804 b, common position shifters 6805 aand 6805 b, individual position shifters 6806 a and 6806 b, and encoders6807 a and 6807 b.

Dividing method determiner 6801 determines a dividing method fordividing the point cloud data. Dividing method determiner 6801 outputsdividing method information indicating the dividing method to divider6802 and shift amount calculators 6804 a and 6804 b. Detailed examplesof the dividing method will be described below. Three-dimensional dataencoding device 6800 need not include dividing method determiner 6801.If dividing method determiner 6801 is not included, three-dimensionaldata encoding device 6800 may use a predetermined dividing method todivide the point cloud data into pieces of divided data.

Divider 6802 divides the point cloud data into pieces of divided dataaccording to the dividing method determined by dividing methoddeterminer 6801. The pieces of divided data created by divider 6802 areindividually processed. For this purpose, three-dimensional dataencoding device 6800 includes processors that process the respectivepieces of divided data. Specifically, for processing a first piece ofdivided data, three-dimensional data encoding device 6800 includesquantizer 6803 a, shift amount calculator 6804 a, common positionshifter 6805 a, individual position shifter 6806 a, and encoder 6807 a.For processing a second piece of divided data, three-dimensional dataencoding device 6800 includes quantizer 6803 b, shift amount calculator6804 b, common position shifter 6805 b, individual position shifter 6806b, and encoder 6807 b. This enables three-dimensional data encodingdevice 6800 to process the pieces of divided data in parallel. AlthoughFIG. 92 shows the exemplary processors for processing two pieces ofdivided data in parallel, three-dimensional data encoding device 6800may include processors for processing three or more pieces of divideddata in parallel. Further, the three-dimensional data encoding devicemay be configured to process each piece of divided data in a singleprocessor.

Each of quantizers 6803 a and 6803 b scales (divides geometryinformation by a certain value) and quantizes the corresponding piece ofdivided data. If multiple points are duplicated, each of quantizers 6803a and 6803 b may delete at least one of the duplicated points or mayleave at least one point unprocessed.

Each of shift amount calculators 6804 a and 6804 b calculates at leastone of a common position shift amount and an individual position shiftamount for shifting, i.e., moving, the position of the correspondingpiece of divided data according to the dividing method determined bydividing method determiner 6801. Shift amount calculators 6804 a and6804 b may calculate only the common position shift amount, only theindividual position shift amount, or both of the common position shiftamount and the individual position shift amount, according to thedividing method.

The common position shift amount is the shift amount (the amount ofmovement) by which the positions of the pieces of divided data areuniformly shifted. That is, the common position shift amount is the samefor the pieces of divided data. The common position shift amountincludes the direction and distance of the shift of the positions of thepieces of divided data. The common position shift amount is an exampleof the first shift amount.

The individual position shift amount is the shift amount (the amount ofmovement) by which the position of each piece of divided data isindividually shifted. The individual position shift amount is determinedin a one-to-one correspondence with each piece of divided data and isoften different for each piece of divided data. The individual positionshift amount includes the direction and distance of the shift of theposition of the corresponding piece of divided data. The individualposition shift amount is an example of the second shift amount.

Each of common position shifters 6805 a and 6805 b shifts the positionof the corresponding piece of divided data by the common position shiftamount calculated by the corresponding one of shift amount calculators6804 a and 6804 b. Thus, pieces of divided data 6811 to 6814 shown in(a) in FIG. 93 created by dividing point cloud data 6810 are shifted ina direction and over a distance as indicated by the common positionshift amount, as shown in (b) in FIG. 93.

Each of individual position shifters 6806 a and 6806 b shifts theposition of the corresponding piece of divided data by the individualposition shift amount calculated by the corresponding one of shiftamount calculators 6804 a and 6804 b. Thus, pieces of divided data 6811to 6814 shown in (c) in FIG. 93 are shifted in a direction and over adistance as indicated by their respective individual shift amounts.

Each of encoders 6807 a and 6807 b encodes the corresponding one of thepieces of divided data shifted by individual position shifters 6806 aand 6806 b.

The order of processing by divider 6802, quantizers 6803 a and 6803 b,shift amount calculators 6804 a and 6804 b, common position shifters6805 a and 6805 b, and individual position shifters 6806 a and 6806 bmay be changed. For example, shift amount calculators 6804 a and 6804 band common position shifters 6805 a and 6805 b may perform processingbefore processing by divider 6802. In this case, shift amountcalculators 6804 a and 6804 b may be merged into one processor, andcommon position shifters 6805 a and 6805 b may be merged into oneprocessor. Also in this case, shift amount calculators 6804 a and 6804 bmay calculate at least the common position shift amount out of thecommon position shift amount and the individual position shift amountbefore processing by common position shifters 6805 a and 6805 b. Theindividual position shift amount may be calculated before processing byindividual position shifters 6806 a and 6806 b. That is, processorsresponsible for calculating the common position shift amount maycalculate the common position shift amount before processing by thecommon position shifters separately from processors responsible forcalculating the individual position shift amounts. Further, any two ormore of the above processors may be merged together.

Now, an example of calculating the common position shift amount and theindividual position shift amounts will be described with reference toFIG. 94. FIG. 94 is a diagram for describing a first example of theposition shift. In the first example, point cloud data 6810 is shiftedby the common position shift amount, and then pieces of divided data6811 to 6814 are shifted by their respective individual position shiftamounts.

As shown in (a) in FIG. 94, the three-dimensional data encoding devicegenerates bounding box 6820 of a size accommodating all pieces ofdivided data 6811 to 6814 of point cloud data 6810, and calculates theminimum value point of bounding box 6820 generated. Thethree-dimensional data encoding device then calculates, as the commonposition shift amount, the direction and distance of a vectorrepresented as the difference between the minimum value point calculatedand the origin. Because the origin is 0, the difference is indicated bythe coordinates of the minimum value point. The origin may also be apredetermined nonzero reference point. Bounding box 6820 may be arectangular region of the minimum size surrounding all pieces of divideddata 6811 to 6814. The minimum value point of bounding box 6820 is thepoint closest to the origin in the region of bounding box 6820. Boundingbox 6820 is also referred to as a common bounding box. A bounding box isalso referred to as a coding bounding box.

As shown in (b) in FIG. 94, the three-dimensional data encoding deviceshifts pieces of divided data 6811 to 6814 by the common position shiftamount calculated. Alternatively, the three-dimensional data encodingdevice may shift undivided point cloud data 6810 by the common positionshift amount.

Then, as shown in (b) in FIG. 94, the three-dimensional data encodingdevice generates, for pieces of divided data 6811 to 6814 uniformlyshifted, respective bounding boxes 6821 to 6824 each having a sizeaccommodating the corresponding one of pieces of divided data 6811 to6814, and calculates the minimum value point of each of bounding boxes6821 to 6824 generated. For each of pieces of divided data 6811 to 6814,the three-dimensional data encoding device calculates, as the individualposition shift amount of the piece of divided data, the distance betweenthe minimum value point of the corresponding bounding box and theorigin. Bounding boxes 6821 to 6824 may each be a rectangular region ofthe minimum size surrounding the corresponding one of pieces of divideddata 6811 to 6814. The minimum value point of each of bounding boxes6821 to 6824 is the point closest to the origin in the region of each ofbounding boxes 6821 to 6824. Bounding boxes 6821 to 6824 are alsoreferred to as individual bounding boxes.

As shown in (c) in FIG. 94, the three-dimensional data encoding deviceshifts pieces of divided data 6811 to 6814 by their respectiveindividual position shift amounts calculated.

The three-dimensional data encoding device uses bounding boxes 6821 to6824 to encode respective pieces of divided data 6811 to 6814 shifted bythe individual position shift amounts, thereby generating a bitstream.At this point, the three-dimensional data encoding device stores, inmetadata in the bitstream, second bounding box information indicatingthe position of the minimum value point of and the size of each ofbounding boxes 6821 to 6824.

Hereafter, bounding boxes will also be referred to as coding boundingboxes (coding BBs).

The common position shift amount, and first bounding box informationindicating the position of the minimum value point of and the size ofbounding box 6820, are stored in the SPS in the data structure of thebitstream shown in (e) in FIG. 94. Each individual position shift amountis stored in the header of geometry information on the correspondingpiece of divided data. The second bounding box information on each oneof bounding boxes 6821 to 6824 used to encode the corresponding one ofpieces of divided data 6811 to 6814 is stored in the header of thegeometry information on the piece of divided data.

The shift amount Shift(i) of a piece of divided data (i) can becalculated using the following equation, where Shift_A is the commonposition shift amount and Shift_B(i) is the individual position shiftamount (i is the index of the piece of divided data).

Shift(i)=Shift_A+Shift_B(i)

That is, as shown in (d) in FIG. 94, the total shift amount of eachpiece of divided data can be calculated by summing the common positionshift amount and the corresponding individual position shift amount.

Before encoding the point cloud data, the three-dimensional dataencoding device shifts the position of the point cloud data of the i-thpiece of divided data by subtracting Shift(i).

A three-dimensional data decoding device can return the piece of divideddata to its original position in the following manner. Thethree-dimensional data decoding device obtains Shift_A and Shift_B(i)from the SPS and from the header of the piece of divided data andcalculates Shift(i), and then adds Shift(i) to the piece of divided data(i) decoded. The pieces of divided data can thus be correctlyreproduced.

Now, a second example of the position shift, involving the commonposition shift but not the individual position shift, will be describedwith reference to FIG. 95. The second example can reduce the informationamount in the bitstream by not sending the individual position shiftamounts.

FIG. 95 is a diagram for describing the second example of the positionshift. In the second example, the position of point cloud data 6810 isshifted by the common position shift amount, but the positions of piecesof divided data 6811 to 6814 are not shifted by the individual positionshift amounts.

As shown in (a) in FIG. 95, the three-dimensional data encoding devicegenerates bounding box 6820 of a size accommodating all pieces ofdivided data 6811 to 6814 of point cloud data 6810, and calculates thecommon position shift amount using bounding box 6820 generated. Thecommon position shift amount is calculated in the manner described withreference to FIG. 94.

As shown in (b) in FIG. 95, the three-dimensional data encoding deviceshifts pieces of divided data 6811 to 6814 by the common position shiftamount calculated, and encodes the divided data using bounding box 6820containing all pieces of divided data 6811 to 6814 uniformly shifted.

As above, in the second example, the dividing of point cloud data 6810is not followed by the calculation of the individual position shiftamount or the bounding box information for each of pieces of divideddata 6811 to 6814. Although the three-dimensional data encoding devicein the second example shifts the positions of pieces of divided data6811 to 6814 by the common position shift amount and encodes pieces ofdivided data 6811 to 6814 using the common bounding box, this is notlimiting. For example, the three-dimensional data encoding device mayshift the positions of pieces of divided data 6811 to 6814 by the commonposition shift amount and encode pieces of divided data 6811 to 6814using bounding boxes for respective pieces of divided data 6811 to 6814.The three-dimensional data encoding device may also shift pieces ofdivided data 6811 to 6814 by their respective individual position shiftamounts and encode pieces of divided data 6811 to 6814 using the commonbounding box.

As shown in (c) in FIG. 95, the total shift amount of each piece ofdivided data is the common position shift amount.

The common position shift amount, and the first bounding box informationindicating the position of the minimum value point of and the size ofbounding box 6820 containing all the pieces of divided data, are storedin the SPS in the data structure of the bitstream shown in (d) in FIG.95

No individual position shift amount, or second bounding box informationfor encoding each piece of divided data, is stored in the header of thegeometry information on the piece of divided data.

The SPS or GPS includes a flag (identification information) indicatingthat the divided data has been encoded using the common position shiftamount and using the bounding box containing all pieces of divided data6811 to 6814. The SPS or GPS also includes a flag (identificationinformation) indicating that no individual position shift amount or sizeinformation on a bounding box for encoding each piece of divided data isstored in the header of the geometry information on the piece of divideddata.

The three-dimensional data decoding device determines, based on theabove flags in the SPS or GPS, whether the divided data has been encodedusing common information or individual information, and calculates, foruse in decoding, geometry information and the bounding box size orsizes.

Hereafter, a BB refers to a bounding box. The common information refersto the common position shift amount and the first BB information, whichare shared by all the pieces of divided data. The common position shiftamount may be represented as the minimum value point of the commonbounding box. The individual information refers to the individualposition shift amount of each piece of divided data, and the second BBinformation on the bounding box for the piece of divided data used forencoding. The individual position shift amount may be represented as theminimum value point of the bounding box for each piece of divided data.Section information refers to information indicating partitions thatdivide the space into pieces of data, and may include BB informationindicating the minimum value point of each BB and the size of each BB.

FIG. 96 is a flowchart illustrating an exemplary encoding method inwhich processing is switched between the first example and the secondexample. FIG. 97 is a flowchart illustrating an exemplary decodingmethod in which processing is switched between the first example and thesecond example.

As shown in FIG. 96, the three-dimensional data encoding devicedetermines the common position shift amount of point cloud data 6810 andthe size of the common BB surrounding point cloud data 6810 (S6801).

The three-dimensional data encoding device determines whether to shiftpieces of divided data 6811 to 6814 individually by their respectiveindividual position shift amounts (S6802). The three-dimensional dataencoding device may make this determination based on the amount ofreduction in header information or based on the result of calculatingthe coding efficiency.

If pieces of divided data 6811 to 6814 are not shifted individually (Noat S6802), the three-dimensional data encoding device determines to sendthe common position shift amount and the size of the common BB (S6803)but not to send individual position shift amounts and the size of thecommon BB (S6804). Consequently, the three-dimensional data encodingdevice generates a bitstream that includes the common position shiftamount and the size of the common BB but does not include individualposition shift amounts and the sizes of individual BBs. The bitstreammay include identification information indicating that no individualshift has been performed.

If pieces of divided data 6811 to 6814 are shifted individually (Yes atS6802), the three-dimensional data encoding device determines to sendthe common position shift amount and the size of the common BB (S6805)and to send the individual position shift amounts and the sizes of theindividual BBs (S6806). Consequently, the three-dimensional dataencoding device generates a bitstream that includes the common positionshift amount and the size of the common BB, as well as the individualposition shift amounts and the sizes of the individual BBs. Thebitstream may include identification information indicating thatindividual shift has been performed. At step S6806, thethree-dimensional data encoding device may calculate the individualposition shift amounts and the sizes of the individual BBs for pieces ofdivided data 6811 to 6814.

As shown in FIG. 97, the three-dimensional data decoding device receivesthe bitstream to obtain the identification information indicatingwhether individual shift has been performed (S6811).

Based on the identification information, the three-dimensional datadecoding device determines whether individual shift has been performedduring the encoding (S6812).

If the three-dimensional data decoding device determines that noindividual shift has been performed for pieces of divided data 6811 to6814 (No at S6812), the three-dimensional data decoding device obtainsthe common position shift amount and the size of the common BB from thebitstream (S6813).

If the three-dimensional data decoding device determines that individualshift has been performed for pieces of divided data 6811 to 6814 (Yes atS6812), the three-dimensional data decoding device obtains the commonposition shift amount and the size of the common BB (S6814) as well asthe individual position shift amounts and the sizes of the individualBBs (S6815) from the bitstream.

Now, a third example of the position shift will be described withreference to FIG. 98. In the third example, the positions are shifted byposition shift amounts determined using sections that divides the spacecontaining the point cloud data. The third example can further reducethe information amount of the position shift amounts.

FIG. 98 is a diagram for describing the third example of the positionshift. In the third example, the total shift amount of each of pieces ofdivided data 6811 to 6814 is represented as a three-step shift amount.

As shown in (a) in FIG. 98, the three-dimensional data encoding devicecalculates the common position shift amount using bounding box 6820. Thecommon position shift amount is calculated in the manner described withreference to FIG. 94. At this point, the three-dimensional data encodingdevice determines sections 6831 to 6834 ((b) in FIG. 98) for dividingpoint cloud data 6810, and divides point cloud data 6810 into pieces ofdivided data 6811 to 6814 according to sections 6831 to 6834 determined.Sections 6831 to 6834 correspond to pieces of divided data 6811 to 6814,respectively. Sections 6831 to 6834 are also referred to as sectionbounding boxes.

As shown in (b) in FIG. 98, the three-dimensional data encoding devicecalculates, as the position shift amount of each of sections 6831 to6834, the direction and distance of a vector represented as thedifference between the minimum value point of bounding box 6820containing all the pieces of divided data and the minimum value point ofthe section.

As shown in (c) in FIG. 98, for pieces of divided data 6811 to 6814, thethree-dimensional data encoding device generates bounding boxes 6821 to6824 each having a size accommodating the corresponding one of pieces ofdivided data 6811 to 6814, and calculates the minimum value point ofeach of bounding boxes 6821 to 6824 generated. Then, for each of piecesof divided data 6811 to 6814, the three-dimensional data encoding devicecalculates, as the individual position shift amount of the piece ofdivided data, the direction and distance of a vector represented as thedifference between the minimum value point of the bounding box for thepiece of divided data and the minimum value point of the correspondingsection.

The three-dimensional data encoding device stores, in a bitstream, thecommon position shift amount, the individual position shift amount ofeach piece of divided data, and the bounding box information indicatingthe size of bounding box 6820.

The common position shift amount, and the first bounding box informationindicating the position of the minimum value point of and the size ofbounding box 6820, are stored in the SPS in the data structure of thebitstream shown in (e) in FIG. 98. The individual position shift amountis stored in the header of the geometry information on each piece ofdivided data. Section information including the position shift amount ofeach section is stored in, for example, a parameter set in whichdivision metadata is stored. The second bounding box information on eachof bounding boxes 6821 to 6824 used to encode the corresponding one ofpieces of divided data 6811 to 6814 is stored in the header of thegeometry information on the piece of divided data. Here, bounding boxes6821 to 6824 used to encode respective pieces of divided data 6811 to6814 are within respective sections 6831 to 6834.

The shift amount Shift(i) of a piece of divided data (i) can becalculated using the following equation, where Shift_A is the commonposition shift amount, Shift_B(i) is the individual position shiftamount, and Shift_C(i) is the section position shift amount (i is theindex of the piece of divided data).

Shift(i)=Shift_A+Shift_B(i)+Shift_C(i)

That is, as shown in (d) in FIG. 98, the total shift amount of eachpiece of divided data can be calculated by summing the three shiftamounts: the common position shift amount, the section position shiftamount, and the individual position shift amount.

Before encoding the point cloud data, the three-dimensional dataencoding device shifts the position of the point cloud data of the i-thpiece of divided data by subtracting Shift(i).

The three-dimensional data decoding device can return the piece ofdivided data to its original position in the following manner. Thethree-dimensional data decoding device obtains Shift_A, Shift_B(i), andShift_C(i) from the SPS and from the header of the piece of divided dataand calculates Shift(i), and then adds Shift(i) to the piece of divideddata (i) decoded. The pieces of divided data can thus be correctlydecoded.

This method sends the section information and indicates each individualposition shift amount as the difference between each piece of divideddata and the corresponding section. This advantageously reduces theinformation amount of the shift amount of each piece of divided data.

The individual position shift amount may be switched as follows. If thesection information is not sent, the individual position shift amountmay be the difference between the minimum value point of the commonbounding box and the minimum value point of each individual boundingbox. If the section information is sent, the individual position shiftamount may be the difference between the minimum value point of eachsection and the minimum value point of the corresponding individualbounding box. In the latter case, the individual position shift amountis represented as the sum of the section position shift amount and thedifference calculated.

FIG. 99 is a flowchart illustrating an exemplary encoding method inwhich individual position shift is switched between the first exampleand the third example. FIG. 100 is a flowchart illustrating an exemplarydecoding method in which individual position shift is switched betweenthe first example and the third example.

As shown in FIG. 99, the three-dimensional data encoding devicedetermines the dividing method for dividing point cloud data 6810(S6821). Specifically, the three-dimensional data encoding devicedetermines whether to shift the positions of the point cloud dataaccording to the first example or the third example.

Based on the dividing method determined, the three-dimensional dataencoding device determines whether the method in the third exampleinvolving sections is used (S6822).

If the method in the first example is determined to be used (No atS6822), the three-dimensional data encoding device sets each individualposition shift amount to the difference between the minimum value pointof the common BB and the minimum value point of each individual BB(S6823).

The three-dimensional data encoding device generates a bitstream thatincludes the common information and the individual information (S6824).The bitstream may include identification information indicating themethod in the first example.

If the method in the third example is determined to be used (Yes atS6822), the three-dimensional data encoding device sets each individualposition shift amount to the difference between the minimum value pointof each section BB and the minimum value point of the correspondingindividual BB (S6825).

The three-dimensional data encoding device sends a bitstream thatincludes the common information, the individual information, and thesection information (S6826). The bitstream may include identificationinformation indicating the method in the third example.

As shown in FIG. 100, the three-dimensional data decoding device obtainsthe bitstream and determines whether the bitstream includes the sectioninformation (S6831). The three-dimensional data decoding device thusdetermines whether the bitstream obtained includes point cloud dataencoded according to the first example or point cloud data encodedaccording to the third example. Specifically, if the bitstream includesthe section information, the device determines that the bitstreamincludes point cloud data encoded according to the third example. If thebitstream does not include the section information, the devicedetermines that the bitstream includes point cloud data encodedaccording to the first example. Alternatively, the three-dimensionaldata decoding device may obtain the identification information in thebitstream to determine whether the bitstream has been encoded accordingto the first example or the third example.

If the bitstream does not include the section information (No at S6831),that is, if the data has been encoded according to the first example,the three-dimensional data decoding device obtains the commoninformation and the individual information from the bitstream (S6832).

Based on the common information and the individual information obtained,the three-dimensional data decoding device calculates the position shiftamount of each piece of divided data, which is the position shift amountShift(i) in the first example, and also calculates the common BB and theindividual BBs. The three-dimensional data decoding device uses theseinformation items to decode the point cloud data (S6833).

If the bitstream includes the section information (Yes at S6831), thatis, if the data has been encoded according to the third example, thethree-dimensional data decoding device obtains the common information,the individual information, and the section information from thebitstream (S6834).

Based on the common information, the individual information, and thesection information obtained, the three-dimensional data decoding devicecalculates the position shift amount of each piece of divided data,which is the position shift amount Shift(i) in the third example, andalso calculates the common BB, the individual BBs, and the sections. Thethree-dimensional data decoding device uses these information items todecode the point cloud data (S6835).

Now, a fourth example of the position shift will be described withreference to FIG. 101. In the fourth example, the positions are shiftedby position shift amounts determined using coding bounding boxes thatare sections dividing the space containing the point cloud data.Compared with the third example, the fourth example can reduce theinformation amount of the bounding boxes because the sections match theindividual bounding boxes.

FIG. 101 is a diagram for describing the fourth example of the positionshift. In the fourth example, the total shift amount of each of piecesof divided data 6811 to 6814 is represented as a two-step shift amountthat includes the common position shift amount and the section positionshift amount.

As shown in (a) in FIG. 101, the three-dimensional data encoding devicecalculates the common position shift amount using bounding box 6820. Thecommon position shift amount is calculated in the manner described withreference to FIG. 94. At this point, the three-dimensional data encodingdevice divides point cloud data 6810 into pieces of divided data 6811 to6814. Point cloud data 6810 is divided in the manner described withreference to (a) in FIG. 98.

As shown in (b) in FIG. 101, the three-dimensional data encoding devicecalculates the section position shift amounts. The section positionshift amounts are calculated in the manner described with reference to(b) in FIG. 98.

The three-dimensional data encoding device calculates the sectionposition shift amounts as the individual position shift amounts ofpieces of divided data 6811 to 6814. Consequently, the three-dimensionaldata encoding device stores, in a bitstream, the common position shiftamount, the individual position shift amounts (the section positionshift amounts), and the bounding box information indicating the sizes ofthe bounding boxes (the sections).

The common position shift amount, and the first bounding box informationindicating the position of the minimum point of and the size of boundingbox 6820, are stored in the SPS in the data structure of the bitstreamshown in (d) in FIG. 101.

Each individual position shift amount is stored in at least one of; theheader of the geometry information on the corresponding piece of divideddata; and the division metadata. If the individual position shift amountis stored in only one of the header of the geometry information and thedivision metadata, the GPS or SPS may include identification informationindicating that the individual position shift amount is stored in theheader of the geometry information on the corresponding piece of divideddata, or identification information indicating that the individualposition shift amount is stored in the division metadata. Alternatively,each individual position shift amount may be stored in, for example, theheader of the corresponding piece of divided data, and the GPS or SPSmay include identification information (a flag) indicating whether theposition shift amount and the bounding box information in the header ofthe piece of divided data match the corresponding section. This allowsthe three-dimensional data decoding device to refer to the flag todetermine that the section information is stored in the header of thepiece of divided data, and use, as the section information, the positionshift amount and the bounding box information in the header of the pieceof divided data. Alternatively, the flag may be stored in the divisionmetadata, and, if the flag is set to 1 indicating that the sectioninformation is stored in the header of the corresponding piece ofdivided data, the three-dimensional data decoding device may refer tothe header of the piece of the divided data to obtain the sectioninformation.

The shift amount Shift(i) of a piece of divided data (i) can becalculated using the following equations, where Shift_A is the commonposition shift amount, Shift_B(i) is the individual position shiftamount, and Shift_C(i) is the section position shift amount (i is theindex of the piece of divided data).

Shift_B(i)=Shift_C(i)

Shift(i)=Shift_A+Shift_B(i)

That is, as shown in (c) in FIG. 101, the total shift amount of eachpiece of divided data can be calculated by summing the common positionshift amount and the section position shift amount (i.e., the individualposition shift amount).

Before encoding the point cloud data, the three-dimensional dataencoding device shifts the position of the point cloud data of the i-thpiece of divided data by subtracting Shift(i).

The three-dimensional data decoding device can return the piece ofdivided data to its original position in the following manner. Thethree-dimensional data decoding device obtains Shift_A, and Shift_B(i)or Shift_C(i), from the SPS and from the header of the piece of divideddata and calculates Shift(i), and then adds Shift(i) to the piece ofdivided data (i) decoded. The pieces of divided data can thus becorrectly decoded.

This method sets the individual position shift amounts to match thesection position shift amounts. This eliminates the need to send, inresponse to a request, section information that would otherwise beneeded, thereby advantageously reducing the information amount.

Note that the method may switch between transmitting, as the individualposition shift amount, the bounding box information on the individualbounding box for each piece of divided data and transmitting the sectioninformation as the individual position shift amount, depending onwhether it is required to send the section information.

FIG. 102 is a flowchart illustrating an exemplary encoding method inwhich the section information is stored and processing is switchedbetween the third example and the fourth example.

As shown in FIG. 102, the three-dimensional data encoding devicedetermines the dividing method for dividing point cloud data 6810(S6841). Specifically, the three-dimensional data encoding devicedetermines whether to shift the positions of the point cloud dataaccording to the third example or the fourth example. Thethree-dimensional data encoding device may make this determination basedon the amount of reduction in header information or based on the resultof calculating the coding efficiency.

Based on the dividing method determined, the three-dimensional dataencoding device determines whether the positions are shifted usingindividual bounding boxes (S6842). That is, the three-dimensional dataencoding device determines whether the method in the third example orthe method in the fourth example is used.

If the method in the third example is determined to be used (Yes atS6842), the three-dimensional data encoding device sets each individualposition shift amount to the difference between the minimum value pointof each section BB and the minimum value point of the correspondingindividual BB (S6843).

The three-dimensional data encoding device generates a bitstream thatincludes the common information, the individual information, and thesection information (S6844). The bitstream may include identificationinformation indicating the method in the third example.

If the method in the fourth example is determined to be used (No atS6842), the three-dimensional data encoding device sets each individualposition shift amount to the difference between the minimum value pointof the common BB and the minimum value point of each section BB (S6845).

The three-dimensional data encoding device sends a bitstream thatincludes the common information and the section information (S6846). Thebitstream may include identification information indicating the methodin the fourth example.

Now, a fifth example of the position shift will be described withreference to FIG. 103. In the fifth example, the positions are shiftedby position shift amounts determined using sections that divides thespace containing the point cloud data. The fifth example can reduce theinformation amount of the shift amounts.

FIG. 103 is a diagram for describing the fifth example of the positionshift. The fifth example is different from the third example in that thesections are equal in size.

As shown in (a) in FIG. 103, the three-dimensional data encoding devicecalculates the common position shift amount using bounding box 6820. Thecommon position shift amount is calculated in the manner described withreference to FIG. 94. At this point, with reference to bounding box 6820and according to a predetermined rule for example, the three-dimensionaldata encoding device determines sections 6841 to 6844 ((b) in FIG. 103)for dividing point cloud data 6810. For example, if bounding box 6820 isto be divided into N sections and if N=4, the three-dimensional dataencoding device can create four sections 6841 to 6844 of the same size.Here, section numbers in Morton order, for example, may be defined asidentifiers for identifying sections 6841 to 6844. Because the sectionsare of the same size, the position shift amount of each section can becalculated from the number of sections and the section number.Therefore, instead of sending the position shift amounts of thesections, the three-dimensional data encoding device may send the numberof sections and identification information for identifying the sections.The identification information is, as described above, the sectionnumbers of sections 6841 to 6844 in Morton order.

In the example in (c) in FIG. 103, the coding regions are bounding boxesfor the respective pieces of divided data. The position shift amount ofeach piece of divided data is represented as the sum of the commonposition shift amount, the position shift amount of the correspondingsection, and the individual position shift amount from the referenceposition (the position of the minimum point) of the correspondingsection. The corresponding section need not include the entire codingregion (i.e., the entire individual BB).

In the example in (d) in FIG. 103, the coding regions for the pieces ofdivided data match the respective sections. The position shift amount ofeach piece of divided data is represented as the sum of the commonposition shift amount and the position shift amount of the correspondingsection. The corresponding section matches the coding region (i.e., theindividual BB) and therefore includes the entire coding region.

As above, the three-dimensional data encoding device may or need not setthe coding regions for the pieces of divided data to match the sectionsdividing the point cloud data. If the coding regions for the pieces ofdivided data are set to match the sections, either the method in (c) inFIG. 103 or the method in (d) in FIG. 103 may be used. If the codingregions for the pieces of divided data are not set to match thesections, the method in (c) in FIG. 103 may be used.

When the method in (c) or (d) in FIG. 103 is used, the common positionshift amount and the bounding box information indicating the position ofthe minimum point of and the size of bounding box 6820 are stored in theSPS in the data structure of the bitstream. Section information,including the dividing method information and the number of sections, isstored in the SPS or GPS as information shared by all the pieces ofdivided data. The number in a predetermined order (Morton order) (theidentification information) of each section is stored, as information onthe section, in the header of the geometry information on thecorresponding piece of divided data.

Each individual position shift amount is stored in the header of thegeometry information on the corresponding piece of divided data.Further, for (c) in FIG. 103, each individual position shift amount isstored in the header of the geometry information on the correspondingpiece of divided data.

If the sections are set to match the pieces of divided data (i.e., ifthe sections are set to match the individual bounding boxes for thepieces of divided data), the number (the tile ID) of each piece ofdivided data in the header of the geometry information on the piece ofdivided data may be regarded as the number of the corresponding sectionin the predetermined order. In this manner, each individual positionshift amount may be indicated by the identification information (thenumber in the predetermined order) on each piece of data. Thisadvantageously reduces the information amount in the header.

The three-dimensional data encoding device may switch the manner ofindicating the position shift amounts as follows. If the dividing methodin the fifth example is used, the three-dimensional data encoding devicemay divide the common bounding box into sections numbered in apredetermined order. The three-dimensional data encoding device may thenindicate the position shift amount of each section as the sectioninformation that includes the number of sections and the sectionidentification information. If any other dividing method is used, thethree-dimensional data encoding device may indicate the position shiftamounts without using the above section information.

The shift amount Shift(i) of a piece of divided data (i) can becalculated using the following equation, where Shift_A is the commonposition shift amount, Shift_B(i) is the individual position shiftamount, and Shift_D(i) is the section position shift amount (i is theindex of the piece of divided data).

Shift(i)=Shift_A+Shift_B(i)+Shift_D(i)

That is, the total shift amount of each piece of divided data can becalculated by summing the three shift amounts: the common position shiftamount, the section position shift amount, and the individual positionshift amount.

Before encoding the point cloud data, the three-dimensional dataencoding device shifts the position of the point cloud data of the i-thpiece of divided data by subtracting Shift(i).

The three-dimensional data decoding device can return the piece ofdivided data to its original position in the following manner. Thethree-dimensional data decoding device obtains Shift_A and Shift_B(i)from the SPS and from the header of the piece of divided data, andfurther obtains the section information that includes the dividingmethod information, the number of sections, and the section number inthe predetermined order. The three-dimensional data decoding device thenderives the position shift amount Shift_D(i) by a predetermined method,calculates Shift(i), and adds Shift(i) to the piece of divided data (i)decoded. The pieces of divided data can thus be correctly decoded.

A detailed example of a rule and a reduction in header amount will bedescribed with respect to the point cloud data divided using an octree.FIG. 104 is a diagram for describing an encoding method for thethree-dimensional space divided using an octree.

First, the three-dimensional data encoding device may offset (shift ormove the position of) the point cloud data in the three-dimensionalspace by the common position shift amount and divide the point clouddata using an octree. The three-dimensional data encoding device usesthe octree to divide bounding box 6850 for the point cloud data intoeight sections. The number of sections is set according to the Depth ofthe octree. For example, the number of sections according to the Depthis given by N=2{circumflex over ( )}(Depth*3), so that the number ofsections is 8 for Depth=1, and 64 for Depth=2. The sections are numberedin Morton order. The geometry information on the sections can becalculated from Morton order by applying the fifth example to thethree-dimensional space. Notably, Morton order can be calculated fromthe geometry information on the sections by a predetermined method.

Information on the bounding box for the point cloud data is stored inthe SPS or GPS that includes metadata shared by all the pieces ofdivided data. The bounding box information includes the minimum valuepoint (the initial position) of and the size of the bounding box.

The three-dimensional data encoding device stores, in the SPS or GPS inthe data structure of the bitstream shown in (e) in FIG. 104,identification information indicating that the dividing method is octreedivision, and, if the dividing method is octree-based, Depth informationindicating the Depth of the octree. The number in Morton order isstored, as the divided-data number, in the header of each piece ofdivided data. In the octree-based dividing method, the position shiftamount of each piece of divided data and the coding bounding boxinformation are to be derived from Morton order and therefore not storedin the bitstream.

Thus, as shown in (f) in FIG. 104, the three-dimensional data encodingdevice uses the geometry information on each octree section and apredetermined method to calculate the identification informationindicating the octree-based dividing method, the Depth of the octree,and the number in Morton order. As shown in (g) in FIG. 104, thethree-dimensional data decoding device obtains the identificationinformation indicating the octree-based dividing method, the Depth ofthe octree, and the number in Morton order. The three-dimensional datadecoding device then uses a predetermined method to reproduce thegeometry information on each octree section.

If a section contains no point cloud data, the corresponding sectioninformation is not required. For example, if the section with thedivided-data number=2 contains no point cloud data, the divided-datanumber is not sent. The sequence of divided-data numbers therefore skips2 and includes 1, 3, 4, and so on.

The division metadata may include the divided-data numbers or mayinclude the section information on all the sections, including sectionscontaining no point cloud data. In the latter case, the sectioninformation may indicate whether each section contains point cloud data.

FIG. 105 is a diagram illustrating an exemplary syntax of the GPS.

octree_partition_flag is a flag indicating whether the point cloud datawas divided using an octree.

depth indicates, if the point cloud data was divided using an octree,the depth of division by the octree.

gheader_BBmin_present_flag is a flag indicating whether the header ofeach piece of geometry information includes a geometry information fieldfor the coding bounding box for the point cloud data.

gheader_BBsize_present_flag is a flag indicating whether the header ofeach piece of geometry information includes a size information field forthe coding bounding box for the point cloud data.

If octree_partition_flag=1, gheader_BBmin_present_flag andgheader_BBsize_present_flag are set to 0.

FIG. 106 is a diagram illustrating an exemplary syntax of the header ofeach piece of geometry information.

partition_id indicates the identification information on the divideddata. For octree-based division, partition_id indicates a uniqueposition in Morton order.

BBmin indicates the shift amount for encoding the data or the divideddata.

BBsize indicates the size of the bounding box for encoding the data orthe divided data.

Although the above description has taken octree-based division as anexample, the above approach can similarly be applied to other dividingmethods by defining a predetermined dividing method, the order of thepieces of divided data, and the manner of calculating the geometryinformation. For example, if the point cloud data is divided at regularintervals in an x-y plane viewed from above, information indicating thisdividing method, the number or size of the sections, and the order ofthe sections may be determined and sent. Based on these informationitems, both the three-dimensional data encoding device and thethree-dimensional data decoding device can calculate the geometryinformation and the position shift amounts. Because no geometryinformation is sent, the amount of data can be reduced. The informationsent may also include information indicating whether the dividing methodis octree-based, information on the plane divided, and information onquadtree-based division.

FIG. 107 is a flowchart illustrating an exemplary encoding method inwhich processing is switched according to whether octree-based divisionis performed. FIG. 108 is a flowchart illustrating an exemplary decodingmethod in which processing is switched according to whether octree-baseddivision was performed.

As shown in FIG. 107, the three-dimensional data encoding devicedetermines the dividing method for dividing the point cloud data(S6851).

Based on the dividing method determined, the three-dimensional dataencoding device determines whether octree-based division is performed(S6852).

If octree-based division is not determined to be performed (No atS6852), the three-dimensional data encoding device sets the individualposition shift amounts to the minimum value points of the individual BBsfor the pieces of divided data, shifts the positions of the pieces ofdivided data, and encodes the pieces of divided data using theindividual BBs (S6853).

The three-dimensional data encoding device stores the common BBinformation in the common metadata (S6854).

The three-dimensional data encoding device stores the individualposition shift amount of each piece of divided data in the header of thepiece of divided data (S6855).

If octree-based division is determined to be performed (Yes at S6852),the three-dimensional data encoding device sets the individual positionshift amounts to the minimum value points of the sections created by anoctree, shifts the positions of the pieces of divided data, and encodesthe pieces of divided data using the octree sections (S6856).

The three-dimensional data encoding device stores the common BBinformation, the identification information indicating the octree-baseddivision, and the Depth information, in the common metadata (S6857).

The three-dimensional data encoding device stores, in the header of eachpiece of divided data, the order information indicating the number inMorton order for determining the individual position shift amount of thepiece of divided data (S6858).

The three-dimensional data decoding device obtains, from the commonmetadata, the information indicating the dividing method used to dividethe point cloud data (S6861).

Based on the information indicating the dividing method obtained, thethree-dimensional data decoding device determines whether the dividingmethod is octree-based (S6862). Specifically, based on theidentification information indicating whether octree-based dividing wasperformed, the three-dimensional data decoding device determines whetherthe dividing method is octree-based.

If the dividing method is not octree-based (No at S6862), thethree-dimensional data decoding device obtains the common BBinformation, the individual position shift amounts, and the individualBB information, and decodes the point cloud data (S6863).

If the dividing method is octree-based (Yes at S6862), thethree-dimensional data decoding device obtains the common BBinformation, the Depth information, and the individual orderinformation, calculates the individual position shift amounts and thecoding BB information, and decodes the point cloud data (S6864).

Any of the methods in the examples described in this embodiment willsuccessfully reduce the code amount. Any one of these methods may beselected in a predetermined manner.

For example, the three-dimensional data encoding device may calculatethe code amount, and, on a predetermined condition that depends on thecode amount calculated, determine to perform the first method of theabove-described methods. As another example, in the case of irreversiblecompression, it may be determined whether the quantization factor isgreater than a predetermined value, whether the number of pieces ofdivided data is greater than a predetermined number, or whether thenumber of point clouds is fewer than a predetermined number. If theseconditions suggest a possible change in overhead, the first method maybe switched to the second method of the above-described methods.

In the above description, the header of each piece of divided dataincludes, as the individual information, the difference between thepiece of divided data and the common information. However, this is notlimitation. Rather, the individual information in the header of eachpiece of divided data may be the difference between the piece of divideddata and the individual information on the preceding piece of divideddata.

FIG. 109 is a diagram illustrating an exemplary data structure of abitstream in which the pieces of divided data are classified into A datacapable of random access and B data incapable of random access. FIG. 110illustrates an example in which the pieces of divided data in FIG. 109are replaced by frames.

In this case, in which one or more random access units exist, the dataheaders of A data and the data headers of B data may include differenttypes of information. For example, each piece of divided data belongingto A data may include difference information on the individualdifference between the piece of divided data and the common informationin the GPS, whereas each piece of divided data belonging to B data mayinclude difference information indicating the difference between thepiece of divided data and A data in the same random-access unit. For arandom-access unit that includes multiple pieces of divided databelonging to B data, each piece of divided data belonging to B data inthe random-access unit may include difference information indicating thedifference between the piece of divided data and A data, or may includedifference information indicating the difference between the piece ofdivided data and the preceding piece of divided data belonging to A or Bdata.

Although the pieces of divided data have been described above, the abovedescription also applies to frames.

This embodiment has been described mainly with reference to the examplesin which the sections or partitions divide the BB containing all thepieces of divided data (FIG. 111). Advantageously, for other types ofsections, the methods in this embodiment will similarly reduce the codeamount.

To divide the BB containing all the pieces of divided data as shown inFIG. 111, the three-dimensional data encoding device may shift thepositions of the pieces of divided data with reference to the minimumvalue of the BB and then divide the point cloud data shifted. If thepoint cloud data is scaled or quantized, the three-dimensional dataencoding device may divide the point cloud data scaled or quantized, ormay divide the point cloud data yet to be scaled or quantized.

As shown in FIG. 112, the three-dimensional data encoding device may setthe sections according to the coordinate system of the input point clouddata. In this case, the three-dimensional data encoding device does notshift the positions with reference to the minimum value point of the BBfor the point cloud data.

As shown in FIG. 113, the three-dimensional data encoding device may setthe sections according to a higher-order coordinate system higher thanthe coordinate system of the point cloud data. For example, thethree-dimensional data encoding device may set the sections based on theGPS coordinates of map data.

In this case, the three-dimensional data encoding device may store, inthe bitstream, relative position information on the point cloudcoordinate system relative to the higher-order coordinate system, andsend the bitstream. For example, a sensor such as an in-vehicle Lidarmay sense the point cloud data while travelling, and thethree-dimensional data encoding device may send sensor positioninformation (the GPS coordinates, acceleration, speed, and travellingdistance) as the relative position information. If the point cloud datahas a time-series frame structure, the three-dimensional data encodingdevice may store, in the bitstream, time-series sensor positioninformation on a frame basis, and send the bitstream. The higher-ordercoordinate system may indicate absolute coordinates, or relativecoordinates based on the absolute coordinates. A coordinate systemfurther higher than the higher-order coordinate system may serve as thehigher-order coordinate system.

As shown in FIG. 114, the three-dimensional data encoding device maydetermine the sections based on objects or data attributes of the pointcloud data. For example, the three-dimensional data encoding device maydetermine the sections based on the result of image recognition. Thesections in this case may include overlapping areas. Thethree-dimensional data encoding device may cluster the points in thepoint clouds based on predetermined attributes, divide the data based onthe number of points, or determine the sections so that the sectionshave substantially the same number of point clouds.

The three-dimensional data encoding device may signal the number ofpoints encoded, and the three-dimensional data decoding device may usethe number of points to decode the point cloud data.

Data to be encoded are set for each frame or for each piece of divideddata created by dividing each frame. The number of points encoded istypically stored in the corresponding data header. The number of pointsencoded may be signaled in the following manner; a reference value maybe stored in the common metadata, and difference information indicatingthe difference between the number of points and the reference value maybe stored in each data header.

For example, as shown in FIG. 115, the three-dimensional data encodingdevice may store the reference number A of points (i.e., the referencevalue) in the GPS or SPS, and store, in each data header, the numberB(i) of points (i is the index of the piece of divided data), which isthe difference between the number of points and the reference number Aof points. The number of points in the piece of divided data (i) isobtained by adding the number B(i) to the number A. Thethree-dimensional data decoding device therefore calculates A+B(i) anddecodes the data using the calculated value as the number of points inthe piece of divided data (i).

Alternatively, as shown in FIG. 116, the three-dimensional data encodingdevice may store, in each data header, difference information indicatingthe difference between the number of points and the number of points inthe preceding piece of divided data. In this case, the number of pointsin the piece of divided data (i) is obtained by adding the numbersB(1)-B(i) in the preceding pieces of divided data to the number A.

If, for example, the point cloud data is time-series data having amulti-frame structure as shown in FIG. 117, the three-dimensional dataencoding device may store, in the common SPS, a reference value of thenumber of points encoded, and store, in the GPS or each data header, arelative value of each frame relative to the reference value. Thethree-dimensional data encoding device may also store, in the GPS, thedifference (a relative value) between each number of points and thereference value stored in the SPS and further store, in each dataheader, the difference (a relative value) between the number of pointsand the sum of the reference value in the SPS and the difference valuein the GPS. This will advantageously reduce the code amount in theoverhead.

One possible manner of dividing the point cloud data is dividing thepoint cloud data into pieces having substantially the same number ofpoints. In this case, a method as in FIG. 115 may be used.

As an example, as shown in FIG. 118, the point cloud data may be dividedsuch that the differences among the numbers of points in the pieces ofdivided data are not greater than one. Δ may be indicated by 1-bit data.For Δ=0, the difference information need not be indicated.

As another example, as shown in FIG. 119, most pieces of divided datamay include the same number of points as the reference number indicatedin the GPS, and the remaining pieces of divided data may indicate thedifference between the number of points and the reference number. ForΔ=0, the difference information need not be indicated.

Any of the above methods in FIGS. 115 to 119 will advantageously reducethe information amount in the overhead.

As stated above, the three-dimensional data encoding device according tothe present embodiment performs the process shown by FIG. 120. Thethree-dimensional data encoding device encodes point cloud dataindicating three-dimensional positions in a three-dimensional space. Thethree-dimensional data encoding device shifts the point cloud data by afirst shift amount (S6871). Next, the three-dimensional data encodingdevice divides the point cloud data into pieces of sub point cloud databy dividing the three-dimensional space into subspaces (S6872). Thethree-dimensional data encoding device shifts each of the pieces of subpoint cloud data by a second shift amount based on a position of one ofthe subspaces that includes the sub point cloud data, the pieces of subpoint cloud data being included in the point cloud data shifted by thefirst shift amount (S6873). The three-dimensional data encoding deviceencodes the pieces of sub point cloud data shifted, to generate abitstream (S6874). The bitstream includes first shift information forcalculating the first shift amount, and pieces of second shiftinformation each for calculating a corresponding one of second shiftamounts by which the pieces of sub point cloud data are shifted and eachof which is the second shift amount. According to this method, thepieces of sub point cloud data created by dividing are encoded afterbeing shifted. This can reduce the amount of geometry information oneach piece of sub point cloud data, thereby improving the codingefficiency.

For example, the subspaces are equal in size. Each of the pieces ofsecond shift information includes first identification information foridentifying a total number of the subspaces and a corresponding one ofthe subspaces. This can reduce the amount of the second shiftinformation, thereby improving the coding efficiency.

For example, the first identification information is a Morton ordercorresponding to each of the subspaces.

For example, each of the subspaces is a space obtained by dividing onethree-dimensional space using an octree. The bitstream includes secondidentification information indicating that the subspace is a spaceobtained by dividing one three-dimensional space using an octree, anddepth information indicating a depth of the octree. As above, the pointcloud data in the three-dimensional space is divided using the octree.This can reduce the amount of geometry information on each piece ofsubspace point cloud data, thereby improving the coding efficiency.

For example, the dividing of the point cloud data is performed after thepoint cloud data is shifted by the first shift amount.

For example, the three-dimensional data encoding device includes aprocessor and memory, and the processor performs the above process usingthe memory.

The three-dimensional data decoding device according to the presentembodiment performs the process shown by FIG. 121. The three-dimensionaldata decoding device decodes pieces of sub point cloud data, first shiftinformation, and second shift information from a bitstream, the piecesof sub point cloud data (i) being obtained by dividing point cloud dataindicating three-dimensional positions by dividing a three-dimensionalspace into subspaces and (ii) being each shifted by a first shift amountand a corresponding second shift amount, the first shift informationbeing for calculating the first shift amount, the pieces of second shiftinformation being each for calculating a corresponding one of secondshift amounts by which the pieces of sub point cloud data are shiftedand each of which is the corresponding second shift amount (S6881). Thethree-dimensional data decoding device reproduces the point cloud databy shifting each of the pieces of sub point cloud data by a shift amountobtained by adding the first shift amount and the corresponding secondshift amount (S6882). According to this method, the point cloud data canbe correctly decoded using the bitstream with improved codingefficiency.

For example, the subspaces are equal in size. Each of the pieces ofsecond shift information includes first identification information foridentifying a total number of the subspaces and a corresponding one ofthe subspaces. This can reduce the amount of the second shiftinformation, thereby improving the coding efficiency.

For example, the first identification information is a Morton ordercorresponding to each of the subspaces.

For example, each of the subspaces is a space obtained by dividing onethree-dimensional space using an octree. The bitstream includes secondidentification information indicating that the subspace is a spaceobtained by dividing one three-dimensional space using an octree, anddepth information indicating a depth of the octree. As above, the pointcloud data in the three-dimensional space is divided using the octree.This can reduce the amount of geometry information on each piece ofsubspace point cloud data, thereby improving the coding efficiency.

For example, the three-dimensional data decoding device includes aprocessor and memory, and the processor performs the above process usingthe memory.

A three-dimensional data encoding device, a three-dimensional datadecoding device, and the like according to the embodiments of thepresent disclosure have been described above, but the present disclosureis not limited to these embodiments.

Note that each of the processors included in the three-dimensional dataencoding device, the three-dimensional data decoding device, and thelike according to the above embodiments is typically implemented as alarge-scale integrated (LSI) circuit, which is an integrated circuit(IC). These may take the form of individual chips, or may be partiallyor entirely packaged into a single chip.

Such IC is not limited to an LSI, and thus may be implemented as adedicated circuit or a general-purpose processor. Alternatively, a fieldprogrammable gate array (FPGA) that allows for programming after themanufacture of an LSI, or a reconfigurable processor that allows forreconfiguration of the connection and the setting of circuit cellsinside an LSI may be employed.

Moreover, in the above embodiments, the structural components may beimplemented as dedicated hardware or may be realized by executing asoftware program suited to such structural components. Alternatively,the structural components may be implemented by a program executor suchas a CPU or a processor reading out and executing the software programrecorded in a recording medium such as a hard disk or a semiconductormemory.

The present disclosure may also be implemented as a three-dimensionaldata encoding method, a three-dimensional data decoding method, or thelike executed by the three-dimensional data encoding device, thethree-dimensional data decoding device, and the like.

Also, the divisions of the functional blocks shown in the block diagramsare mere examples, and thus a plurality of functional blocks may beimplemented as a single functional block, or a single functional blockmay be divided into a plurality of functional blocks, or one or morefunctions may be moved to another functional block. Also, the functionsof a plurality of functional blocks having similar functions may beprocessed by single hardware or software in a parallelized ortime-divided manner.

Also, the processing order of executing the steps shown in theflowcharts is a mere illustration for specifically describing thepresent disclosure, and thus may be an order other than the shown order.Also, one or more of the steps may be executed simultaneously (inparallel) with another step.

A three-dimensional data encoding device, a three-dimensional datadecoding device, and the like according to one or more aspects have beendescribed above based on the embodiments, but the present disclosure isnot limited to these embodiments. The one or more aspects may thusinclude forms achieved by making various modifications to the aboveembodiments that can be conceived by those skilled in the art, as wellforms achieved by combining structural components in differentembodiments, without materially departing from the spirit of the presentdisclosure.

Although only some exemplary embodiments of the present disclosure havebeen described in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of the present disclosure. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to a three-dimensional dataencoding device and a three-dimensional data decoding device.

What is claimed is:
 1. A three-dimensional data encoding method ofencoding point cloud data indicating three-dimensional positions in athree-dimensional space, the three-dimensional data encoding methodcomprising: shifting the point cloud data by a first shift amount;dividing the point cloud data into pieces of sub point cloud data bydividing the three-dimensional space into subspaces; shifting each ofthe pieces of sub point cloud data by a second shift amount based on aposition of one of the subspaces that includes the sub point cloud data,the pieces of sub point cloud data being included in the point clouddata shifted by the first shift amount; and encoding the pieces of subpoint cloud data shifted, to generate a bitstream, wherein the bitstreamincludes first shift information for calculating the first shift amount,and pieces of second shift information each for calculating acorresponding one of second shift amounts by which the pieces of subpoint cloud data are shifted and each of which is the second shiftamount.
 2. The three-dimensional data encoding method according to claim1, wherein the subspaces are equal in size, and each of the pieces ofsecond shift information includes first identification information foridentifying a total number of the subspaces and a corresponding one ofthe subspaces.
 3. The three-dimensional data encoding method accordingto claim 2, wherein the first identification information is a Mortonorder corresponding to each of the subspaces.
 4. The three-dimensionaldata encoding method according to claim 1, wherein each of the subspacesis a space obtained by dividing one three-dimensional space using anoctree, and the bitstream includes second identification informationindicating that the subspace is a space obtained by dividing onethree-dimensional space using an octree, and depth informationindicating a depth of the octree.
 5. The three-dimensional data encodingmethod according to claim 1, wherein the dividing of the point clouddata is performed after the point cloud data is shifted by the firstshift amount.
 6. A three-dimensional data decoding method, comprising:decoding pieces of sub point cloud data, first shift information, andsecond shift information from a bitstream, the pieces of sub point clouddata (i) being obtained by dividing point cloud data indicatingthree-dimensional positions by dividing a three-dimensional space intosubspaces and (ii) being each shifted by a first shift amount and acorresponding second shift amount, the first shift information being forcalculating the first shift amount, the pieces of second shiftinformation being each for calculating a corresponding one of secondshift amounts by which the pieces of sub point cloud data are shiftedand each of which is the corresponding second shift amount; andreproducing the point cloud data by shifting each of the pieces of subpoint cloud data by a shift amount obtained by adding the first shiftamount and the corresponding second shift amount.
 7. Thethree-dimensional data decoding method according to claim 6, wherein thesubspaces are equal in size, and each of the pieces of second shiftinformation includes first identification information for identifying atotal number of the subspaces and a corresponding subspace.
 8. Thethree-dimensional data decoding method according to claim 7, wherein thefirst identification information is a Morton order corresponding to eachof the subspaces.
 9. The three-dimensional data decoding methodaccording to claim 6, wherein each of the subspaces is a space obtainedby dividing one three-dimensional space using an octree, and thebitstream includes second identification information indicating that thesubspace is a space obtained by dividing one three-dimensional spaceusing an octree, and depth information indicating a depth of the octree.10. A three-dimensional data encoding device that encodes point clouddata indicating three-dimensional positions in a three-dimensionalspace, the three-dimensional data encoding device comprising: aprocessor; and memory, wherein using the memory, the processor: shiftsthe point cloud data by a first shift amount; divides the point clouddata into pieces of sub point cloud data by dividing thethree-dimensional space into subspaces; shifts each of the pieces of subpoint cloud data by a second shift amount based on a position of one ofthe subspaces that includes the sub point cloud data, the pieces of subpoint cloud data being included in the point cloud data shifted by thefirst shift amount; and encodes the pieces of sub point cloud datashifted, to generate a bitstream, wherein the bitstream includes firstshift information for calculating the first shift amount, and pieces ofsecond shift information each for calculating a corresponding one ofsecond shift amounts by which the pieces of sub point cloud data areshifted and each of which is the second shift amount.
 11. Athree-dimensional data decoding device, comprising: a processor; andmemory, wherein using the memory, the processor: decodes pieces of subpoint cloud data, first shift information, and second shift informationfrom a bitstream, the pieces of sub point cloud data (i) being obtainedby dividing point cloud data indicating three-dimensional positions bydividing a three-dimensional space into subspaces and (ii) being eachshifted by a first shift amount and a corresponding second shift amount,the first shift information being for calculating the first shiftamount, the pieces of second shift information being each forcalculating a corresponding one of second shift amounts by which thepieces of sub point cloud data are shifted and each of which is thecorresponding second shift amount; and reproduces the point cloud databy shifting each of the pieces of sub point cloud data by a shift amountobtained by adding the first shift amount and the corresponding secondshift amount.